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Prenatal Exposure to Select Phthalates and Phenols and Associations with Fetal and Placental Weight among Male Births in the EDEN Cohort (France).

Introduction

Placental Weight and Placental Efficiency

The placenta is the main interface between the mother and the fetus. This organ performs crucial physiological functions such as nutrient, oxygen, and waste transportation during pregnancy (Jansson and Powell 2007). The placenta also produces, metabolizes, and regulates transfer of various hormones such as estrogens, progesterone, and human chorionic gonadotropin (hCG) (Murphy et al. 2006), which are crucial for fetal development. The placental-to-birth weight ratio (PFR) has been used as a proxy measure of placental efficiency with the common idea that decreased PFR reflects increased placental activity and nutrient transfer capacity, whereas increased PFR indicates less efficient placenta (Hayward et al. 2016). U-shaped associations have been observed between PFR and several perinatal outcomes such as fetal death (Haavaldsen et al. 2013) and preeclampsia (Dahlstrom et al. 2008). Regarding placental weight, both extreme low and high placental weights have been associated with adverse health outcomes. Low placental weight was associated with increased risk of preterm preeclampsia (Dahlstrom et al. 2008), cryptorchidism (Arendt et al. 2016; Ghazarian et al. 2018) and hypospadias among males at birth (Arendt et al. 2016), whereas high placental weight has been associated with lower Apgar scores at birth (Eskild et al. 2014) and increased risk of term preeclampsia (Dahlstrom et al. 2008).

Placental Weight Regulation

In toxicological studies, modifications of the environment during pregnancy, such as induced hypoxia, modification of the circulating levels of glucocorticoid and insulin-like growth factors as well as diet restriction, could affect placental weight (Fowden and Forhead 2009). Environmental contaminants might also play a role as suggested by epidemiological studies reporting associations between air pollutants, cigarette smoking, and placental weight (Christianson 1979; Rahmalia et al. 2012; Spira et al. 1975; van den Hooven et al. 2012; Yorifuji et al. 2012). Here, we focused on two other families of contaminants, phenols and phthalates, with prevalent exposure in the general population (Casas et al. 2013; CDC 2014). Data regarding associations between these compounds and markers of placental growth in humans are sparse (Zhu et al. 2018; Ferguson et al. 2018).

Sources of Exposures to Select Phenols and Phthalates

Several phenols are manufactured in high volume with wide industrial applications. Triclosan is a biocide used in antiseptic wash products (e.g., antibacterial soaps), deodorants, household cleaners, laundry detergents, kitchenware, and some fabrics and toys (Dhillon et al. 2015). Parabens are used as preservatives in cosmetics, personal care products, food, and some pharmaceuticals (Andersen 2008). Benzophenone-3 is an ultraviolet light filter used in sunscreen, clear plastic packaging, and other products to prevent damage to color and scent (e.g., soap, perfumes) (IARC 2013). Bisphenol A is frequently used as the monomer of polycarbonate plastic.

Esters of phthalic acids, commonly called phthalates, are used as plasticizers in polyvinyl chloride plastics, household and car building materials, personal care products, solvents for ink and paints, and some medical devices (Hauser and Calafat 2005).

Associations between Exposure to Phenols and Phthalates and Placental Weight

To our knowledge, only two epidemiological studies, one focusing on phthalates (Zhu et al. 2018) and the other on phenols (Ferguson et al. 2018), examined the associations between environmental exposure to these compounds and markers of placental growth. Zhu et al. (2018) reported associations between maternal urinary concentrations of several phthalate metabolites [mono-butyl phthalate (MBP), mono-methyl phthalate, and di-2-ethylhexyl phthalate (DEHP) metabolites] and placental length, breadth, and thickness among 2,725 pregnant women. Both positive and negative associations were observed depending on the phthalate, timing of exposure (first, second, or third trimester of pregnancy), and sex of the baby (Zhu et al. 2018). Ferguson et al. (2018) assessed exposure to 10 phenols or their precursors (four parabens, triclosan, triclocarban, bisphenol S, two dichlorophenols, and benzophenone-3) and reported decreased placental weight with prenatal exposure to triclosan among girls and increased placental weight with prenatal exposure to butylparaben among boys (Ferguson et al. 2018, 2019). This study had a low sample size with only 49 boys and 42 girls included but not necessarily low validity given the high accuracy of exposure assessment provided by repeated measures of the chemical biomarkers (n = 3 urine samples per women).

Objective

We explored the associations between urinary concentrations of phthalate and phenol biomarkers during pregnancy and placental weight and PFR at birth among 473 male newborns. We also reported associations with the weight of the fetuses at birth.

Population and Methods

The EDEN Cohort

We relied on a subgroup of the EDEN (Etude des Determinants pre et postnatals du developpement et de la sante de l'Enfant) mother-child cohort, which consists of pregnant women recruited from April 2003 to March 2006 in the obstetrical departments of the university hospitals of Nancy and Poitiers, France. Participation was proposed to all potentially eligible women visiting the prenatal clinics of Nancy and Poitiers university hospitals before their 24th week of gestation [assessed by the date of the last menstrual period (LMP)]. Exclusion criteria were multiple pregnancies, known diabetes before pregnancy, French illiteracy, or planning to move out of the region within the next 3 y (Heude et al. 2016). The cohort was approved by the relevant ethical committees (Comite Consultatif pour la Protection des Personnes dans la Recherche Biomedicale, Le Kremlin-Bicetre University hospital, and Commission Nationale de l'Informatique et des Libertes).

Study Population

The current study was restricted to a subgroup of 473 mother-son pairs of the EDEN cohort for which placental weight and information on phenol and phthalate exposure biomarkers during pregnancy were available. Phenol and phthalate metabolite urinary concentrations were only available for mother-son pairs because they were assessed in the framework of a previous project that aimed at investigating the associations of these compounds on male congenital malformations (Chevrier et al. 2012).

Main Outcomes: Placental Weight, Birth Weight and PFR

Placental and birth weight were obtained at birth from hospital maternity records (Rahmalia et al. 2012). Placental weight was not collected as part of the original cohort protocol and is not recorded systematically in French maternity clinics, and the frequency of this measure differed between our two recruitment centers (missing for 43% of births in Nancy compared with 7% of births in Poitiers). PFR was computed as [placental weight (g)/birthweight (g)] X 100.

Quantification of Phenol and Phthalate Biomarkers

Women were asked to collect a sample of their first morning urine at home before the first study visit, which occurred at the hospital between 23 and 29 gestational weeks. Women who did not collect their urine at home collected a spot sample at the hospital during the visit (n = 66, 14%). Urine samples were aliquoted and stored at -80[degrees]C before shipment on dry ice to the National Center for Environmental Health laboratory at the CDC in Atlanta, Georgia. The analysis of blinded specimens at the CDC laboratory was determined not to constitute engagement in human subjects research.

Urinary concentrations of 11 phthalate metabolites, including {mono(3-carboxypropyl) phthalate (MCPP), MBP, mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), monoethyl phthalate (MEP), monocarboxy-isononyl phthalate (MCNP), monocarboxy-isooctyl phthalate (MCOP), and four metabolites of DEHP [mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP)]}; nine phenols (two dichlorophenols, bisphenol A, benzophenone-3, triclosan and four parabens); and creatinine, a marker of urine dilution, were assessed at the CDC as described in detail in previous publications (Silvaetal. 2007; Yeetal. 2005).

Biomarker Concentrations, Imputation and Standardization

Instrumental reading values were used to replace biomarker concentrations below the limit of detection. Instrumental reading values equal to zero (i.e., indicative of no signal) were replaced by the lowest instrumental reading value provided for a given analyte divided by the square root of 2.

We standardized the biomarker concentrations on sampling conditions before analysis using a two-step standardization method based on regression residuals (Mortamais et al. 2012). This standardization consisted of a) studying the associations between each sampling condition and the measured biomarker concentrations using adjusted linear regression models, and b) using the estimated effects of sampling conditions that were associated with urine concentrations (p < 0.2) and the measured biomarker concentrations to predict the concentrations that would have been obtained if all women had collected their urine sample under the same conditions. The sampling conditions considered were hour of sampling, day of sampling, year of sample analysis at the CDC, gestational age at collection, duration of storage at room temperature before freezing, and creatinine concentration. This standardization has been used in previous publications (Botton et al. 2016; Philippat et al. 2014).

We computed the molar sums (micromoles per liter) of the two dichlorophenols ([SIGMA] dicholorophenols), the four parabens ([SIGMA] parabens), and the four DEHP metabolites ([SIGMA] DEHP), which were strongly correlated within each group (see Table S1). The other biomarkers were studied individually.

Adjustment Factors

Adjustment factors were the same for all outcomes and were chosen a priori, including variables likely to be common causes of both the exposures and the outcomes without being likely consequences thereof and factors that were possible predictors of the outcomes only. The selected factors were gestational duration (linear and squared terms), maternal prepregnancy weight (broken stick model with a knot at 60 kg) and height (continuous), maternal age (continuous), maternal active (never, 1-5, [greater than or equal to]6 cigarettes per day) and passive smoking during pregnancy (yes/no), maternal education level (high school or less, up to 2 y after high school, [greater than or equal to]3 y after high school), parity (0, 1, [greater than or equal to]2) and recruitment center (Nancy, Poitiers). Gestational duration was estimated using the date of LMP or gestational duration assessed by the obstetrician if it differed from the LMP-based estimate by more than 2 weeks (Philippat et al. 2012). Our analysis was restricted to those having nonmissing values for these adjustment factors (Table 1 shows the frequency of missing values).

Selection Bias Correction

The high frequency of missing placental weight in Nancy (43% of the births) compared with Poitiers (7%) led to an overrepresentation of women from Poitiers, who were less likely to smoke and were on average older compared with the original EDEN cohort (p-values for Pearson's chi-squared or Wilcoxon rank-sum test [less than or equal to]0.2; Table 1). To correct this overrepresentation that may lead to selection bias, we used inverse probably weighting (IPW). IPW assigns a weight to each participant equal to the inverse of the probability of being included in the analysis (Hernan and Robins 2018). We computed the probability of being included using a logistic regression model adjusted for predictors of both placental weight missingness and placental weight (Hernan and Robins 2018), specifically, recruitment center, mode of delivery (normal or cesarean vs. assisted), months of delivery (July/ August vs. rest of the year), reanimation at birth (yes/no), gestational duration (linear + squared term), active (never, 1-5, [greater than or equal to]6 cigarettes per day) and passive (yes/no) smoking, maternal age (continuous), maternal education level (high school or less, up to 2 y after high school, [greater than or equal to]3 years after high school), and parity (0, 1, [greater than or equal to]2). IPW was used in all of our analyses.

Main Statistical Analysis

We used adjusted Elastic Net (ENET)-penalized regression models to detect which biomarker concentrations were associated with placental weight, birth weight, or PFR, simultaneously taking into account all biomarker concentrations. ENET is a penalized regression model relying on a weighted mixture of the least absolute shrinkage and selection operator (LASSO) and ridge penalties. The LASSO penalty allows variable selection through shrinkage. The lowest regression coefficients, corresponding to the least informative predictors, are attributed a zero value and only the most informative predictors are retained by the model. The ridge penalty accommodates correlated exposures and shrinks regression coefficients from correlated predictors proportionally toward zero (Agier et al. 2016; Lenters et al. 2014). The overall penalty ([lambda]) and the mixing proportion for the LASSO and ridge penalties ([alpha]) of our ENET model were determined by minimizing the prediction root mean squared error (RMSE) using 10-fold cross validation. To ensure a stable selection of the [alpha] and [lambda] parameters, we repeated this cross validation 100 times (Lenters et al. 2016). Given the exploratory character of our analysis (only two previous studies have explored the associations between environmental exposure to phenols and phthalates and placental weight) we used the [[lambda].sub.min] value (a value that gives the minimum mean cross-validated error), which is supposed to lead to less parsimonious variable selection than [[lambda].sub.1se] (largest value of lambda that gives an error within 1 standard error of the minimum). We used the R package glmnet. To obtain final effect estimates for each outcome that were not shrunken, we fitted a linear regression model that was simultaneously adjusted for all exposure variables selected by ENET plus our set of a priori confounders (Lenters et al. 2016). We report all associations retained by the ENET model, without regard to the p-values of the unpenalized effect estimates.

Sensitivity Analyses

In sensitivity analyses, we estimated center-specific effects by adding interaction terms between the selected biomarker concentrations and center into the unpenalized linear regression model. For comparison with previous publications, we performed the classical approach that consists of running one linear regression per outcome and exposure in combination with a false-discovery rate (FDR) correction (Benjamini and Hochberg 1995). Each outcome was considered separately for the FDR correction. We referred to this approach as the EWAS (exposome-wide association study) approach.

To check that our results were not driven by extreme values of IPW, we ran an analysis where the extreme low and high values of IPW were assigned the values of the first (extreme low) or the 99th (extreme high) IPW percentile.

To draw our conclusion we gave more weight to associations that were previously described in the literature, namely the positive associations between parabens (Ferguson et al. 2018, 2019), MBP, and DEHP metabolites (Zhu et al. 2018) with placental growth markers.

All analyses were performed using R (version 3.3.1; R Development Core Team) and STATA/SE (version 14; StataCorp.).

Results

Population

Among the 473 mother-son pairs, average gestational age at delivery [plus or minus the standard deviation ([+ or -] SD)] was 39.8 weeks [+ or -] 1.50, average birth weight was 3,373 g [+ or -] 477, average placental weight at birth was 545 g [+ or -] 111, and mean PFR was 16.2 [+ or -] 2.79 (Table 1). Pearson correlation coefficients were 0.58 for placental weight and birth weight, -0.16 for birth weight and PFR, and 0.71 for placental weight and PFR. Just over half (52%) of the women in the study had completed at least 2 y of education after high school and 45% of the women included were nulliparous. Most of the women (85%) did not smoke during pregnancy.

Phenol and Phthalate Metabolite Urinary Concentrations

Frequency of detection of phenols and phthalate biomarkers ranged from 71% to 100% (Table 2). Compared with the mothers from the EDEN cohort with biomarker concentrations but missing placental weight, the concentrations of 2,5 dichlorophenol; sum of dichlorophenols; triclosan; methyl, ethyl, and propyl paraben; sum of parabens; and low-molecular-weight phthalate metabolites (MEP, MBP, MiBP) were lower in our study population (p-values for Wilcoxon rank-sum test <0.10). No difference was observed for the other biomarkers (p-values for Wilcoxon rank-sum test [greater than or equal to]0.18; Table 2).

We observed Spearman correlation coefficients >0.5 between the concentrations of the two dichlorophenols, the four parabens, the four DEHP metabolites, as well as between MBP and MCPP, which are both metabolites of di-n-butyl phthalate (MCPP being also a metabolite of di-n-octyl phthalate and other high-molecular-weight phthalates). Correlation coefficients between the other biomarker concentrations were lower than 0.45 (see Table S1).

Associations between Phthalate and Phenol Exposure Biomarkers and Placental Weight, Birth Weight, and PFR

Among the 13 exposure biomarkers studied, the sum of parabens, triclosan, benzophenone-3, and MCNP were retained by the multipollutant ENET model for placental weight (Table 3). Spearman correlation coefficients between these four biomarkers were all [less than or equal to] 0.20 (see Table S1). Unpenalized effect estimates obtained from the regression model simultaneously adjusted for these four biomarkers were positive for the sum of parabens {[beta] = 7.12 g [95% confidence interval (CI): 0.41,13.9] for a 1-unit increase in the lntransformed concentration} and benzophenone-3 [[beta] = 4.76 g (95% CI:-1.77,11.3)] and negative for triclosan [[beta] = - 4.11 g(95% CI: -8.26, 0.05)] and MCNP [[beta] = -10.9 g (95% CI: -21.8, 0.09)] (Table 3).

Regarding birth weight, benzophenone-3 was the only biomarker selected by the multipollutant ENET model. The associated unpenalized effect estimate was 21.0 g (95% CI: -3.45, 45.5) (Table 3).

The ENET model for PFR selected two biomarkers: MCOP and MCNP (Table 3). The corresponding unpenalized effect estimates were -0.23 (95% CI: -0.58, 0.11), and -0.20 (95% CI: -0.54, 0.13), respectively. The Spearman correlation coefficient for MCOP and MCNP was 0.42.

Sensitivity Analyses

Results of the sensitivity analysis in which the extreme low and high values of IPW were assigned the values of the first or the 99th IPW percentile were similar to those of the main analysis (i.e., the same compounds were selected by ENET; see Table S2).

Results of the EWAS analysis were similar for birth weight and PFR to those of our main analysis relying on ENET (see Table S3). Benzophenone-3 was positively associated with birth weight, whereas MCOP and MCNP were negatively associated with PFR. Only two biomarkers (the sum of parabens and MCNP) were associated with placental weight (p <0.1; see Table S3) compared with the four (the sum of parabens, MCNP, benzophenone-3 and triclosan) selected by ENET (Table 3). None of the associations highlighted in this sensitivity analysis remained significant after FDR correction; the lowest corrected p-value was 0.39 (see Table S3).

All p-values for interactions between center and biomarker concentrations were above 0.2 (see Table S4), except for triclosan and benzophenone-3 in the model on placental weight (p for interaction = 0.02 and 0.06, respectively). In analyses stratified by center, triclosan was not associated with placental weight in Poitiers ([beta] = 0.05 g (95% CI: -4.72, 4.83; n = 315), whereas in Nancy (n = 142) each 1-unit increase in the ln-transformed triclosan concentration was associated with a -9.72 g (95% CI: -17.8, -1.58) decrease in placental weight. Similarly, benzophenone-3 was not associated with placental weight in Poitiers [[beta] = - 0.04 g (95% CI: -7.57, 7.49)] but was positively associated with this outcome in Nancy [[beta] = 6.27 g (95% CI: -4.83, 17.4)].

Discussion

Previous studies reported that butylparaben (Ferguson et al. 2018, 2019) and MBP and DEHP metabolites (Zhu et al. 2018) were positively associated with placental weight, whereas our findings based on data from 473 male births support a positive association between summed parabens and placental weight but no associations with MBP, DEHP, and placental weight. Some novel associations were also suggested: we observed positive associations between benzophenone-3 and placental weight, whereas MCNP and triclosan were negatively associated with this outcome. MCNP and MCOP were negatively associated with PFR, whereas benzophenone-3 was positively associated with birth weight. The fact that the direction of the associations with placental weight differed across biomarkers with some exhibiting positive (the sum of parabens, benzophenone-3) and other negative (triclosan, MCNP) associations with placental weight might reflect different mechanisms of action.

Sum of Parabens

We observed a positive association between the sum of parabens and placental weight. This positive association is in agreement with previous findings among 49 mother-son pairs that reported increased placental weight with prenatal exposure to butylparaben (Ferguson et al. 2018, 2019). In the study by Ferguson et al. (2018) each paraben was studied separately, whereas in our study we used the molar sum of the four parabens. The molar sum limited the number of comparisons done but prevented us from providing an effect estimate per paraben. A study exploring associations between maternal urinary concentration of parabens and placental DNA methylation reported a decrease in the methylation of a region coding for a growth factor involved in both placental and fetal growth [Insulin Growth Factor differentially methylated region (/GF2-DMR2) (LaRocca et al. 2014)].

To our knowledge, this is the first study exploring the associations between parabens and PFR. Regarding birth weight, four studies, like ours, did not report any association (Ferguson et al. 2018; Wu et al. 2017; Geer et al. 2017; Aker et al. 2018), whereas one suggested a nonsignificant increase in birth weight in association with prenatal exposure to parabens among boys of the EDEN cohort (Philippat et al., 2014).

Triclosan

We observed a negative association of triclosan with placental weight. In the sensitivity analysis by center, the association was observed in Nancy but not in Poitiers center. Negative association between triclosan and placental weight has been previously reported; however, the association was sex specific and only observed among girls (Ferguson et al. 2018, 2019). In mice, lower placental weight at gestational day (GD) 19 has been reported in the group exposed to triclosan (GD 6 to 18, 8 mg/kg per day) compared with controls. No effect was observed at lower doses (1 and 4 mg/kg per day) (Cao et al. 2017). In vitro studies also suggested that triclosan induced cytotoxic, antiproliferative and apoptotic effects on human placental cell lines (Honkisz et al. 2012). Findings from these epidemiological, toxicological, and in vitro studies all suggest that triclosan could negatively affect placental weight; however, the inconsistency between the two recruitment centers observed in our study and the fact that Ferguson et al. (2018) reported an association among girls, whereas ours is among boys, warrant investigation in other cohorts.

Triclosan was not clearly associated with either birth weight or PFR in our study population. To our knowledge, this is the first study exploring the association between triclosan and PFR. Regarding birth weight, three previous studies reported no association with triclosan (Geer et al. 2017; Lassen et al. 2016; Philippat et al. 2014), while two reported a negative association (Etzel et al. 2017; Ferguson et al. 2018). Negative associations have also been reported between triclosan and other growth markers, specifically, birth length (Etzel et al. 2017), and head circumference at birth (Etzel et al. 2017; Lassen et al. 2016; Philippat et al. 2014).

Benzophenone 3

We observed a positive association between benzophenone-3 and both placental weight and child birth weight. The association with placental weight was center specific and only observed among mother-son pairs from Nancy.

No association was observed between benzophenone-3 and placental weight in the study by Ferguson et al. (2018) and, to our knowledge, no other study has considered this association. Regarding birth weight, in agreement with our results, a positive association between benzophenone-3 and birth weight was reported among 367 mother-child pairs from New York City (Wolff et al. 2008), whereas two other studies with sample sizes of 459 (Ferguson et al. 2018) and 564 (Tang et al. 2013) reported null associations.

Phthalates

Our results for phthalates were not in line with previous findings; the phthalates associated with placental size in the study by Zhu et al. (2018) were not associated with placental weight in our study. Differences across studies included the markers of placental growth used. We relied on placental weight and PFR, whereas Zhu et al. (2018) studied placental length, breadth, and thickness but not placental weight.

We observed a negative association between two other phthlate metbolites (MCNP and MCOP) and PFR. These metabolites were not measured in the study by Zhu et al. (2018), preventing results comparisons. Given the lack of epidemiological data and the fact that MCNP and MCOP were, with MCPP, the phthalate metabolites with the lowest median concentrations in our study population, our results regarding any associations with PFR need to be replicated.

Strengths

This study is one of the first exploring the associations between environmental exposure to phenols and phthalates and placental weight. Strengths of this study included a) the sample size [473 boys, compared with 49 in the previous study on phenols (Ferguson et al. 2018)], b) the number of biomarkers assessed (20), and c) the use of ENET to select exposure variables associated with the outcomes. In a setting with some correlations between exposures, compared with the classical EWAS approach in which each exposure is considered separately, ENET is supposed to limit on-average FDR (Agier et al. 2016). In practice, in our study population, no association remained significant in our EWAS sensitivity analysis, whereas a few biomarkers were selected with ENET. Discrepancies between the two approaches might come from the fact that FDR correction applied in the EWAS approach considers all associations as independent without taking into account correlations between exposures and between outcomes to correct for the effective number of tests.

Limitations

In a context of weak and possible sex-specific associations, we considered that an approach restricted to a single sex was preferable over two analyses of about half the original sample size stratified on sex. Restricting our analysis to boys prevents generalization of our findings to girls, but is not a source of selection bias. Selection bias usually occurs when conditioning the study participation on a common effect of the exposure and the outcome [or a collider of the exposure and the outcome (Hernan and Robins 2018)], but sex is not a consequence of any of our outcomes. The high frequency of missing placental weight in Nancy led to an underrepresentation of mother-son pairs from this recruitment center in our study population compared with the original EDEN cohort. To limit the risk of selection bias, this underrepresentation was corrected using IPW. We assessed placental weight and were missing other placental characteristics such as placental diameter, thickness, shape, and vascularization, which are also important for the regulation of the exchanges between the mother and the fetus. A delay in the weighing of the placenta after delivery is likely to cause a lower weight estimate because blood will gradually leak from the placenta. Unfortunately, we did not have access to the time elapsed between placenta expulsion and weighing and were not able to study the impact of this delay on our results. We measured phenols and phthalate metabolites in a single spot urine sample collected during pregnancy. Given the strong within-subject variability of the studied chemicals (Adibi et al. 2008; Philippat et al. 2013; Vernet et al. 2018) and the likely episodic nature of the exposures, our results are expected to be affected by exposure misclassification. However, if, as is likely, exposure measurement error is of classical type, it should have led to effect estimates that were biased towards the null and to loss of power, without expected increase in type 2 error (Perrier et al. 2016). Finally, although minimized by the use of ENET, the risk of chance findings existed (Agier et al. 2016), which is why we gave more weight to the association previously reported in the literature in the results interpretation.

Conclusions

We observed an association between several phenols and phthalate metabolites and both placental weight (MCNP, triclosan, sum of parabens, benzophenone-3) and birth weight (benzophenone-3). The positive association between sum of parabens and placental weight was consistent with findings reported by a previous study for butylparaben and placental weight in 49 male newborns, while the other associations were not consistent with previous studies and thus should be seen as hypothesis generating. The inconsistency between the two recruitment centers observed in our study for some associations (triclosan, benzophenone-3, and placental weight), the low sample size of the previous epidemiological study reporting a similar association for parabens, and the fact that this is one of the first report of associations between the other biomarkers and placental weight and PFR call for cautious interpretation of the results. Additional studies relying on repeated assessments of exposure in prospective mother-child cohorts are needed to substantiate the plausibility of the hypotheses generated by our study.

Acknowledgments

We are indebted to the midwife research assistants for data collection and to P. Lavoine and J. Sahuquillo for checking, coding, and data entry and to A. Forhan and L. Giorgis-Allemand for data management. We also would like to acknowledge X. Ye, M. Silva, E. Samandar, J. Preau, and T. Jia (Centers for Disease Control and Prevention, Atlanta, GA) for their work in quantifying the phenol and phthalate biomarkers.

This research was supported by grants from the French Agency for Food, Environmental and Occupational Health & Safety (ANSES, grant EST-2010/2/126), Fondation de France (grant 2015-00059545), and the French National Research Agency in the framework of the Investissements d'Avenir program (ANR-15-IDEX-02). The Eden cohort is supported by grants from FRM, Inserm, IReSP, Nestle, French Ministry of health, ANR, Universite Paris-Sud, French Institute for Public Health Surveillance (InVS), ANSES and Mutuelle generale de l'Education nationale (MGEN). The funding sources had no role in the study design, collection, or interpretation of data; in the writing of the report; or in the decision to submit the paper for publication. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

The EDEN Mother-Child Cohort Study Group includes: I. Annesi-Maesano, J. Bernard, J. Botton, M.A. Charles, P. Dargent-Molina, B. de Lauzon-Guillian, P. Ducimetiere, M. de Agostini, B. Foliguet, A. Forhan, X. Fritel, A. Germa, V. Goua, R. Hankard, B. Heude, M. Kaminski, B. Larroque, N. Lelong, J. Lepeule, F. Pierre, L. Marchand, C. Nabet, R. Slama, M.J. Saurel-Cubizolles, M. Schweitzer and O. Thiebaugeorge.

References

Adibi JJ, Whyatt RM, Williams PL, Calafat AM, Camann D, Herrick R, et al. 2008. Characterization of phthalate exposure among pregnant women assessed by repeat air and urine samples. Environ Health Perspect 116(4):467-473, PMID: 18414628, https://doi.org/10.1289/ehp.10749.

Agier L, Portengen L, Chadeau-Hyam M, Basagana X, Giorgis-Allemand L, Siroux V, et al. 2016. A systematic comparison of linear regression-based statistical methods to assess exposome-health associations. Environ Health Perspect 124(12):1848-1856, PMID: 27219331, https://doi.org/10.1289/EHP172.

Aker AM, Ferguson KK, Rosario ZY, Mukherjee B, Alshawabkeh AN, Cordero JF, et al. 2018. The associations between prenatal exposure to triclocarban, phenols and parabens with gestational age and birth weight in northern Puerto Rico. Environ Res 169:41-51, PMID: 30412856, https://doi.org/10.1016/j.envres. 2018.10.030.

Andersen A. 2008. Final amended report on the safety assessment of methylparaben, ethylparaben, propylparaben, isopropylparaben, butylparaben, isobutylparaben, and benzylparaben as used in cosmetic products. Int J Toxicol 27(suppl 4):1-82, PMID: 19101832, https://doi.org/10.1177/109158180802704s01.

Arendt LH, Ramlau-Hansen CH, Wilcox AJ, Henriksen TB, Olsen J, Lindhard MS. 2016. Placental weight and male genital anomalies: a nationwide Danish cohort study. Am J Epidemiol 183(12):1122-1128, PMID: 27257113, https://doi.org/10. 1093/aje/kwv336.

Benjamini Y, Hochberg Y. 1995. Controlling the false discovery rate--a practical and powerful approach to multiple testing. J R Stat Soc Series B Stat Methodol 57(1):289-300, https://doi.org/10.1111/j.2517-6161.1995.tb02031.x.

Botton J, Philippat C, Calafat AM, Carles S, Charles MA, Slama R, et al. 2016. Phthalate pregnancy exposure and male offspring growth from the intrauterine period to five years of age. Environ Res 151:601-609, PMID: 27596487, https://doi.org/10.1016/j.envres.2016.08.033.

Cao X, Hua X, Wang X, Chen L. 2017. Exposure of pregnant mice to triclosan impairs placental development and nutrient transport. Sci Rep 7:44803, PMID: 28322267, https://doi.org/10.1038/srep44803.

Casas M, Chevrier C, Hond ED, Fernandez MF, Pierik F, Philippat C, et al. 2013. Exposure to brominated flame retardants, perfluorinated compounds, phthalates and phenols in European birth cohorts: ENRIECO evaluation, first human biomonitoring results, and recommendations. Int J Hyg Environ Health 216(3):230-242, PMID: 22795704, https://doi.org/10.1016/j.ijheh.2012.05.009.

CDC (Centers for Disease Control and Prevention). 2014. "Fourth National Report on Human Exposure to Environmental Chemicals Updated Tables, August, 2014." http://www.cdc.gov/exposurereport/pdf/fourthreport_updatedtables_aug2014.pdf [accessed 14 November 2014].

Chevrier C, Petit C, Philippat C, Mortamais M, Slama R, Rouget F, et al. 2012. Maternal urinary phthalates and phenols and male genital anomalies. Epidemiology 23(2):353-356, PMID: 22317818, https://doi.org/10.1097/EDE.0b013e318246073e.

Christianson RE. 1979. Gross differences observed in the placentas of smokers and nonsmokers. Am J Epidemiol 110(2):178-187, PMID: 463872, https://doi.org/10. 1093/oxfordjournals.aje.a112802.

Dahlstrem B, Romundstad P, Oian P, Vatten LJ, Eskild A. 2008. Placenta weight in pre-eclampsia. Acta Obstet Gynecol Scand 87(6):608-611, PMID: 18568459, https://doi.org/10.1080/00016340802056178.

Dhillon GS, Kaur S, Pulicharla R, Brar SK, Cledon M, Verma M, et al. 2015. Triclosan: current status, occurrence, environmental risks and bioaccumulation potential. Int J Environ Res Public Health 12(5):5657-5684, PMID: 26006133, https://doi.org/10.3390/ijerph120505657.

Eskild A, Haavaldsen C, Vatten LJ. 2014. Placental weight and placental weight to birthweight ratio in relation to Apgar score at birth: a population study of 522 360 singleton pregnancies. Acta Obstet Gynecol Scand 93(12):1302-1308, PMID: 25244579, https://doi.org/10.1111/aogs.12509.

Etzel TM, Calafat AM, Ye X, Chen A, Lanphear BP, Savitz DA, et al. 2017. Urinary triclosan concentrations during pregnancy and birth outcomes. Environ Res 156:505-511, PMID: 28427038, https://doi.org/10.1016/j.envres.2017.04.015.

Ferguson KK, Meeker JD, Cantonwine DE, Mukherjee B, Pace GG, Weller D, et al. 2018. Environmental phenol associations with ultrasound and delivery measures of fetal growth. Environ Int 112:243-250, PMID: 29294443, https://doi.org/ 10.1016/j.envint.2017.12.011.

Ferguson KK, Meeker JD, Cantonwine DE, Mukherjee B, Pace GG, Weller D, et al. 2019. Corrigendum to "Environmental phenol associations with ultrasound and delivery measures of fetal growth" [Environment International 112 (2018)243250]. Environ Int 122:418, PMID: 30594295, https://doi.org/10.1016/j.envint.2018. 11.064.

Fowden AL, Forhead AJ. 2009. Endocrine regulation of feto-placental growth. Horm Res 72(5):257-265, PMID: 19844111, https://doi.org/10.1159/000245927.

Geer LA, Pycke BFG, Waxenbaum J, Sherer DM, Abulafia O, Halden RU. 2017. Association of birth outcomes with fetal exposure to parabens, triclosan and triclocarban in an immigrant population in Brooklyn, New York. J Hazard Mater 323(pt A):177-183, PMID: 27156397, https://doi.org/10.1016/j.jhazmat.2016. 03.028.

Ghazarian AA, Trabert B, Graubard BI, Longnecker MP, Klebanoff MA, McGlynn KA. 2018. Placental weight and risk of cryptorchidism and hypospadias in the Collaborative Perinatal Project. Am J Epidemiol 187(7):1354-1361, PMID: 29584806, https://doi.org/10.1093/aje/kwy005.

Haavaldsen C, Samuelsen SO, Eskild A. 2013. Fetal death and placental weight/ birthweight ratio: a population study. Acta Obstet Gynecol Scand 92(5):583-590, PMID: 23398315, https://doi.org/10.1111/aogs.12105.

Hauser R, Calafat AM. 2005. Phthalates and human health. Occup Environ Med 62(11):806-818, PMID: 16234408, https://doi.org/10.1136/oem.2004.017590.

Hayward CE, Lean S, Sibley CP, Jones RL, Wareing M, Greenwood SL, et al. 2016. Placental adaptation: what can we learn from birthweight:placental weight ratio? Front Physiol 7:28, PMID: 26903878, https://doi.org/10.3389/fphys.2016.00028.

Hernan MA, Robins JM. 2018. Causal Inference. Boca Raton: Chapman & Hall/CRC, forthcoming.

Heude B, Forhan A, Slama R, Douhaud L, Bedel S, Saurel-Cubizolles MJ, et al. 2016. Cohort profile: the EDEN mother-child cohort on the prenatal and early postnatal determinants of child health and development. Int J Epidemiol 45(2):353-363, PMID: 26283636, https://doi.org/10.1093/ije/dyv151.

Honkisz E, Zieba-Przybylska D, Wojtowicz AK. 2012. The effect of triclosan on hormone secretion and viability of human choriocarcinoma JEG-3 cells. Reprod Toxicol 34(3):385-392, PMID: 22677473, https://doi.org/10.1016/j.reprotox.2012. 05.094.

IARC (International Agency for Research on Cancer). 2013. Benzophenone. IARC Monogr Eval Carcinog Risk Hum 101:285-304.

Jansson T, Powell TL. 2007. Role of the placenta in fetal programming: underlying mechanisms and potential interventional approaches. Clin Sci (Lond) 113(1):113, PMID: 17536998, https://doi.org/10.1042/CS20060339.

LaRocca J, Binder AM, McElrath TF, Michels KB. 2014. The impact of first trimester phthalate and phenol exposure on IGF2/HI9 genomic imprinting and birth outcomes. Environ Res 133:396-406, PMID: 24972507, https://doi.org/10.1016/j. envres.2014.04.032.

Lassen TH, Frederiksen H, Kyhl HB, Swan SH, Main KM, Andersson AM, et al. 2016. Prenatal triclosan exposure and anthropometric measures including anogenital distance in Danish infants. Environ Health Perspect 124(8):1261-1268, PMID: 26908126, https://doi.org/10.1289/ehp.1409637.

Lenters V, Portengen L, Rignell-Hydbom A, Jonsson BA, Lindh CH, Piersma AH, et al. 2016. Prenatal phthalate, perfluoroalkyl acid, and organochlorine exposures and term birth weight in three birth cohorts: multi-pollutant models based on elastic net regression. Environ Health Perspect 124(3):365-372, PMID: 26115335, https://doi.org/10.1289/ehp.1408933.

Lenters V, Portengen L, Smit LA, Jonsson BA, Giwercman A, Rylander L, et al. 2014. Phthalates, perfluoroalkyl acids, metals and organochlorines and reproductive function: a multipollutant assessment in Greenlandic, Polish and Ukrainian men. Occup Environ Med 72(6):385-393, PMID: 25209848, https://doi.org/10.1136/oemed-2014-102264.

Mortamais M, Chevrier C, Philippat C, Petit C, Calafat AM, Ye X, et al. 2012. Correcting for the influence of sampling conditions on biomarkers of exposure to phenols and phthalates: a 2-step standardization method based on regression residuals. Environl Health 11:29, PMID: 22537080, https://doi.org/10.1186/ 1476-069X-11-29.

Murphy VE, Smith R, Giles WB, Clifton VL. 2006. Endocrine regulation of human fetal growth: the role of the mother, placenta, and fetus. Endocr Rev 27(2):141169, PMID: 16434511, https://doi.org/10.1210/er.2005-0011.

Perrier F, Giorgis-Allemand L, Slama R, Philippat C. 2016. Within-subject pooling of biological samples to reduce exposure misclassification in biomarker-based studies. Epidemiology 27(3):378-388, PMID: 27035688, https://doi.org/10.1097/ EDE.0000000000000460.

Philippat C, Botton J, Calafat AM, Ye X, Charles MA, Slama R, et al. 2014. Prenatal exposure to phenols and growth in boys. Epidemiology 25(5):625-635, PMID: 25061923, https://doi.org/10.1097/EDE.0000000000000132.

Philippat C, Mortamais M, Chevrier C, Petit C, Calafat A, Ye X, et al. 2012. Exposure to phthalates and phenols during pregnancy and offspring size at birth. Environ Health Perspect 120(3):464-470, PMID: 21900077, https://doi.org/10.1289/ehp. 1103634.

Philippat C, Wolff MS, Calafat AM, Ye X, Bausell R, Meadows M, et al. 2013. Prenatal exposure to environmental phenols: concentrations in amniotic fluid and variability in urinary concentrations during pregnancy. Environ Health Perspect 121(10):1225-1231, PMID: 23942273, https://doi.org/10.1289/ehp.1206335.

Rahmalia A, Giorgis-Allemand L, Lepeule J, Philippat C, Galineau J, Hulin A, et al. 2012. Pregnancy exposure to atmospheric pollutants and placental weight: an approach relying on a dispersion model. Environ Int 48:47-55, PMID: 22836169, https://doi.org/10.1016/j.envint.2012.06.013.

Silva MJ, Samandar E, Preau JL Jr, Reidy JA, Needham LL, Calafat AM. 2007. Quantification of 22 phthalate metabolites in human urine. J Chromatogr B AnalytTechnol Biomed Life Sci 860(1):106-112, PMID: 17997365, https://doi.org/ 10.1016/j.jchromb.2007.10.023.

Spira A, Spira N, Goujard J, Schwartz D. 1975. Smoking during pregnancy and placental weight: a multivariate analysis on 3759 cases. J Perinat Med 3(4):237241, PMID: 1225957, https://doi.org/10.1515/jpme.1975.3A237.

Tang R, Chen MJ, Ding GD, Chen XJ, Han XM, Zhou K, et al. 2013. Associations of prenatal exposure to phenols with birth outcomes. Environ Pollut 178:115-120, PMID: 23562958, https://doi.org/10.1016Zj.envpol.2013.03.023.

van den Hooven EH, Pierik FH, de Kluizenaar Y, Hofman A, van Ratingen SW, Zandveld PY, et al. 2012. Air pollution exposure and markers of placental growth and function: the Generation R Study. Environ Health Perspect 120(12):1753-1759, PMID: 22922820, https://doi.org/10.1289/ehp.1204918.

Vernet C, Philippat C, Calafat AM, Ye X, Lyon-Caen S, Siroux V, et al. 2018. Withinday, between-day, and between-week variability of urinary concentrations of phenol biomarkers in pregnant women. Environ Health Perspect 126(3):037005, PMID: 29553460, https://doi.org/10.1289/EHP1994.

Wolff MS, Engel SM, Berkowitz GS, Ye X, Silva MJ, Zhu C, et al. 2008. Prenatal phenol and phthalate exposures and birth outcomes. Environ Health Perspect 116(8):1092-1097, PMID: 18709157, https://doi.org/10.1289/ehp.11007.

Wu C, Huo W, Li Y, Zhang B, Wan Y, Zheng T, et al. 2017. Maternal urinary paraben levels and offspring size at birth from a Chinese birth cohort. Chemosphere 172:29-36, PMID: 28061343, https://doi.org/10.1016/j.chemosphere.2016.12.131.

Ye X, Kuklenyik Z, Needham LL, Calafat AM. 2005. Quantification of urinary conjugates of bisphenol A, 2,5-dichlorophenol, and 2-hydroxy-4-methoxybenzophenone in humans by online solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. Anal Bioanal Chem 383(4):638644, PMID: 16132150, https://doi.org/10.1007/s00216-005-0019-4.

Yorifuji T, Naruse H, Kashima S, Murakoshi T, Tsuda T, Doi H, et al. 2012. Residential proximity to major roads and placenta/birth weight ratio. Sci Total Environ 414:98-102, PMID: 22142650, https://doi.org/10.1016/j.scitotenv.2011.11.001.

Zhu YD, Gao H, Huang K, Zhang YW, Cai XX, Yao HY, et al. 2018. Prenatal phthalate exposure and placental size and shape at birth: a birth cohort study. Environ Res 160:239-246, PMID: 29028488, https://doi.org/10.1016/j.envres.2017.09.012.

Claire Philippat, (1) Barbara Heude, (2, 3) Jeremie Botton, (4) Nadia Alfaidy, (5) Antonia M. Calafat, (6) Remy Slama, (1) and the EDEN Mother-Child Cohort Study Group

(1) Team of Environmental Epidemiology applied to Reproduction and Respiratory Health, Institute for Advanced Biosciences (IAB), Inserm U1209, Centre national de la recherche scientifique (CNRS) Unite de recherche (UMR) 5309, Universite Grenoble Alpes, Grenoble, France

(2) Early Origin of the Child's Health and Development (ORCHAD) Team, Inserm 1153 Epidemiology and Biostatistics Sorbonne Paris Cite Research Centre (CRESS), Villejuif, France

(3) Universite Paris Descartes, Villejuif, France

(4) Faculty of Pharmacy, Universite Paris-Sud/Universite Paris-Saclay, Chatenay-Malabry, France

(5) Commissariat a l'Energie Atomique et aux Energies Alternatives, CNRS, Inserm U1036, Biosciences and Biotechnology Institute of Grenoble, Universite Grenoble Alpes, Grenoble, France

(6) Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Address correspondence to C. Philippat, Institute for Advanced Biosciences, Site Sante, Allee des Alpes, 38700, La Tronche, Grenoble, France. Telephone: +33 4 76 54 94 51. Email: claire.philippat@inserm.fr

Supplemental Material is available online (https://doi.org/10.1289/EHP3523).

The authors declare they have no actual or potential competing financial interests.

Received 16 February 2018; Revised 5 December 2018; Accepted 6 December 2018; Published 9 January 2019.

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Table 1. Characteristics of live singleton male births from the EDEN
(Etude des Determinants pre et postnatals du developpement et de la
sante de l'Enfant) cohort who were included and excluded from the
present analysis.

Characteristic                               Included (N = 473)

                                          n (%) or mean [+ or -] SD

Recruitment center
 Poitiers                                 326          (69)
 Nancy                                    147          (31)
Mode of delivery
 Normal                                   345          (73)
 Assisted                                  49          (10)
 Caesarean                                 79          (17)
 Missing
Parity
 0                                        215          (45)
 1                                        172          (36)
 [greater than or equal to]2               85          (18)
 Missing                                   1           (0)
Maternal education
 <2 y after high school                   220          (47)
 High school + 2 y                        102          (22)
 [greater than or equal to]               143          (30)
 High school + 3 y
 Missing                                   8           (2)
Maternal BMI (kg/[m.sup.2])
 <18.5                                     45          (10)
 [greater than or equal to]18.5 to <25    294          (62)
 [greater than or equal to]25             125          (26)
 Missing                                   9           (2)
Active smoking during pregnancy
 No                                       402          (85)
 Yes                                       71          (15)
 Missing                                   0           (0)
Passive smoking during pregnancy
 No                                       357          (75)
 Yes                                      115          (24)
 Missing                                   1           (0)
Maternal age (y)                          29.6    [+ or -] 4.86
Gestational duration (weeks) (b)          39.8    [+ or -] 1.50
Birth weight (g)                          3,373   [+ or -] 477
Placental weight (g)                      545     [+ or -] 111
PFR (c)                                   16.2    [+ or -] 2.79

Characteristic                               Excluded (N = 525)

                                          n (%) or mean [+ or -] SD

Recruitment center
 Poitiers                                  207        (39)
 Nancy                                     318        (61)
Mode of delivery
 Normal                                    366        (70)
 Assisted                                  61         (12)
 Caesarean                                 96         (18)
 Missing                                    2          (0)
Parity
 0                                         221        (42)
 1                                         202        (38)
 [greater than or equal to]2               102        (19)
 Missing                                    0          (0)
Maternal education
 <2 y after high school                    239        (46)
 High school + 2 y                         117        (22)
 [greater than or equal to]                154        (29)
 High school + 3 y
 Missing                                   15          (3)
Maternal BMI (kg/[m.sup.2])
 <18.5                                     47          (9)
 [greater than or equal to]18.5 to <25     340        (65)
 [greater than or equal to]25              126        (24)
 Missing                                   12          (2)
Active smoking during pregnancy
 No                                        426        (81)
 Yes                                       97         (18)
 Missing                                    2          (0)
Passive smoking during pregnancy
 No                                        330        (63)
 Yes                                       188        (36)
 Missing                                    7          (1)
Maternal age (y)                          29.0       [+ or -] 4.95
Gestational duration (weeks) (b)          39.5       [+ or -] 2.07
Birth weight (g)                          3,309      [+ or -] 584
Placental weight (g)                      537 (d)    [+ or -] 146
PFR (c)                                   16.5 (d)   [+ or -] 3.30

Characteristic
                                            p-Values
                                              (a)

Recruitment center                           <0.001
 Poitiers
 Nancy
Mode of delivery                              0.59
 Normal
 Assisted
 Caesarean
 Missing
Parity                                        0.54
 0
 1
 [greater than or equal to]2
 Missing
Maternal education                            0.93
 <2 y after high school
 High school + 2 y
 [greater than or equal to]
 High school + 3 y
 Missing
Maternal BMI (kg/[m.sup.2])                   0.63
 <18.5
 [greater than or equal to]18.5 to <25
 [greater than or equal to]25
 Missing
Active smoking during pregnancy
 No                                           0.14
 Yes
 Missing
Passive smoking during pregnancy             <0.001
 No
 Yes
 Missing
Maternal age (y)                             0.10
Gestational duration (weeks) (b)             0.33
Birth weight (g)                             0.25
Placental weight (g)                         0.31
PFR (c)                                      0.39

Note: Male births included in the present study were restricted to
those with non-missing placental weight and assessments of phenols and
phthalate metabolites in urine. BMI: body mass index, PFR:
placental-to-birth weight ratio; LMP, last menstrual period; SD:
standard deviation.

(a) Categorical variables: Pearson's chi-squared p-values; continuous
variables: Wilcoxon rank-sum test p-values.

(b) Based on the date of the LMP, or gestational duration assessed by
the obstetrician if it differed from the LMP-based estimate by more
than 2 weeks.

(c) PFR = [placental weight(g)/birthweight(g)] x 100.

(d) n = 281 because, among the boys not included, only 281 had a
placental weight reported.

Table 2. Urinary phenols and phthalate metabolite concentrations among
mother-son pairs of the EDEN (Etude des Determinants pre et postnatals
du developpement et de la sante de l'Enfant) cohort with (N = 473) and
without (N = 131) placental weight information.

                                             Study population
                                               Percentiles
                                            ([micro]g/L (a))

Analyte              LOD        % >LOD    n     5th     50th   95th
                 ([micro]g/L)

Phenols
2,4-DCP              0.2          98     473    0.23    0.95   9.00
2,5-DCP              0.2         100     473    1.67    9.04   279
[SIGMA]DCP            --          --     473    0.01    0.06   1.78
([micro]mol/L)
BPA                  0.4          99     473    0.83    2.34   9.76
BP3                  0.4          92     473    0.22    2.23   79.4
TCS                  2.3          79     473    0.15    25.5   686
MP                    1          100     473    7.52    100    1232
EP                    1           71     473    0.08    3.11   65.4
PP                   0.2          99     473    0.40    12.0   263
BP                   0.2          85     473    0.09    1.63   57.6
[SIGMA]PB             --          --     473    0.06    0.82   10.2
([micro]mol/L)
Phthalates
MEP                  0.6         100     473    21.2    94.0   713
MBP                  0.2         100     473    11.7    43.4   454
MiBP                 0.2         100     473    11.8    39.4   170
MBzP                 0.3         100     473    4.47    18.2   100
MCPP                 0.2         100     473    0.68    1.97   10.0
MEHP                 0.5          98     473    1.30    7.40   33.7
MEHHP                0.2         100     473    6.41    27.7   98.5
MEOHP                0.2         100     473    5.28    22.9   81.6
MECPP                0.2         100     473    12.0    38.9   156
[SIGMA]DEHP           --          --     473    0.09    0.33   1.19
([micro]mol/L)
MCOP                 0.2         100     473    1.17    3.86   17.4
MCNP                 0.2          99     473    0.49    1.26   10.2

                     Mothers of the EDEN
                   cohort with biomarker
                    concentrations  but
                 missing placental weight
               Percentiles ([micro]g/L (a))

                                             p-Values
Analyte           n     5th    50th   95th     (b)

Phenols
2,4-DCP          131   0.35    1.01   8.39   0.20
2,5-DCP          131   2.84    11.8    227   0.09
[SIGMA]DCP       131   0.02    0.08   1.44   0.08
([micro]mol/L)
BPA              131   0.86    2.37   7.86   0.53
BP3              131   0.12    2.32   69.1   0.94
TCS              131   1.27    30.9    750   0.03
MP               131   9.39     150   1515   0.04
EP               131   0.08    4.69   68.7   0.02
PP               131   0.84    18.5    226   0.02
BP               131   0.09    2.13   57.6   0.34
[SIGMA]PB        131   0.06    1.41   11.8   0.04
([micro]mol/L)
Phthalates
MEP              131   28.8     133    968   0.04
MBP              131   15.5    49.7    423   0.07
MiBP             131   15.1    48.9    175   0.01
MBzP             131   5.25    19.3    114   0.30
MCPP             131   0.72    1.91   9.14   0.68
MEHP             131   1.44    7.69   38.1   0.48
MEHHP            131   7.25    25.6    116   0.95
MEOHP            131   6.39    21.2   90.6   0.68
MECPP            131   13.1    37.9    169   0.64
[SIGMA]DEHP      131   0.10    0.31   1.37   0.70
([micro]mol/L)
MCOP             131   1.31    4.21   20.3   0.18
MCNP             131   0.56    1.34   10.9   0.69

Note: --, not applicable; LOD, Limit of detection; 2,4-DCP,
2,4-dichlorophenol; 2,5-DCP, 5-dichlorophenol; BP, butyl paraben; BP3,
benzophenone 3; BPA, bisphenol A; EP, ethyl paraben; MBP, mono-n-butyl
phthalate; MBzP, monobenzyl phthalate; MCNP, monocarboxyisononyl
phthalate; MCOP, monocarboxy-isooctyl phthalate; MCPP,
mono(3-carboxypropyl) phthalate; MECPP, mono(2-ethyl-5-carboxypentyl)
phthalate; MEHHP; MEHHP, mono(2-ethyl-5-hydroxyhexyl) phthalate; MEHP,
mono(2-ethylhexyl) phthalate; MEOHP and MECPP; MEOHP,
mono(2-ethyl-5-oxohexyl) phthalate; MEP, monoethyl phthalate; MiBP,
mono-isobutyl phthalate; MP, methyl paraben; PP, propyl paraben; TCS,
triclosan; [SIGMA]DCP, molar sum of dichlorophenols; [SIGMA]DEHP, molar
sum of MEHP; [SIGMA]PB, molar sum of parabens (methyl-, ethyl-, propyl-
and butylparaben).

(a) Concentrations are given in [micro]g/L for all compounds but the
sums of dichlorophenols, of parabens, and of DEHP metabolites.

(b) p-Values for the Wilcoxon rank-sum test.

Table 3. Associations of phenol and phthalate metabolite concentrations
with birth weight, placental weight, and placental-to-birth weight
ratio (PFR).

                                  Penalized effect estimates

                              Birth      Placental
Analyte                     weight (g)   weight (g)   PFR (a)

Phenols
[SIGMA]DCP ([micro]mol/L)       0            0           0
BPA ([micro]g/L)                0            0           0
BP3 ([micro]g/L)               2.52         0.65         0
TCS ([micro]g/L)                0          -0.44         0
[SIGMA]PB ([micro]mol/L)        0           1.74         0
Phthalate metabolites
MEP ([micro]g/L)                0            0           0
MBP ([micro]g/L)                0            0           0
MiBP ([micro]g/L)               0            0           0
MBzP ([micro]g/L)               0            0           0
MCPP ([micro]g/L)               0            0           0
DEHP ([micro]mol/L)             0            0           0
MCOP ([micro]g/L)               0            0         -0.04
MCNP ([micro]g/L)               0          -4.76       -0.04

                                   Birth weight (g)

Analyte                     [beta]      95% CI       p-Values

Phenols
[SIGMA]DCP ([micro]mol/L)     --          --            --
BPA ([micro]g/L)              --          --            --
BP3 ([micro]g/L)             21.0    (-3.45; 45.5)     0.09
TCS ([micro]g/L)              --          --            --
[SIGMA]PB ([micro]mol/L)      --          --            --
Phthalate metabolites
MEP ([micro]g/L)              --          --            --
MBP ([micro]g/L)              --          --            --
MiBP ([micro]g/L)             --          --            --
MBzP ([micro]g/L)             --          --            --
MCPP ([micro]g/L)             --          --            --
DEHP ([micro]mol/L)           --          --            --
MCOP ([micro]g/L)             --          --            --
MCNP ([micro]g/L)             --          --            --

                               Unpenalized effect estimates

                                Placental weight (g)

Analyte                     [beta]       95% CI       p-Values

Phenols
[SIGMA]DCP ([micro]mol/L)     --           --            --
BPA ([micro]g/L)              --           --            --
BP3 ([micro]g/L)             4.76     (-1.77; 11.3)     0.15
TCS ([micro]g/L)             -4.11    (-8.26; 0.05)     0.05
[SIGMA]PB ([micro]mol/L)     7.12     (0.41 ; 13.9)     0.04
Phthalate metabolites
MEP ([micro]g/L)              --           --            --
MBP ([micro]g/L)              --           --            --
MiBP ([micro]g/L)             --           --            --
MBzP ([micro]g/L)             --           --            --
MCPP ([micro]g/L)             --           --            --
DEHP ([micro]mol/L)           --           --            --
MCOP ([micro]g/L)             --           --            --
MCNP ([micro]g/L)            -10.9    (-21.8; 0.09)     0.05

                                       PFR (a)

Analyte                     [beta]     95% CI      p-Values

Phenols
[SIGMA]DCP ([micro]mol/L)    --          --           --
BPA ([micro]g/L)             --          --           --
BP3 ([micro]g/L)             --          --           --
TCS ([micro]g/L)             --          --           --
[SIGMA]PB ([micro]mol/L)     --          --           --
Phthalate metabolites
MEP ([micro]g/L)             --          --           --
MBP ([micro]g/L)             --          --           --
MiBP ([micro]g/L)            --          --           --
MBzP ([micro]g/L)            --          --           --
MCPP ([micro]g/L)            --          --           --
DEHP ([micro]mol/L)          --          --           --
MCOP ([micro]g/L)           -0.23   (-0.58; 0.11     0.18
MCNP ([micro]g/L)           -0.20   (-0.54; 0.13     0.23

Note: Both the penalized estimates from the multipollutant elastic net
(ENET) penalized regression model and the estimates from the
unpenalized linear regression models for the biomarkers selected by
ENET are presented. Parameters are reported for an increase by 1 in the
ln-transformed biomarker concentration. N = 457 mother-son pairs of the
EDEN (Etude des Determinants pre et postnatals du developpement et de
la sante de l'Enfant) cohort. Data were restricted to mother-son pairs
with no missing value for covariates. All models were adjusted for
gestational age, maternal active and passive smoking, maternal age,
weight and height, maternal education, parity, and recruitment center.
We used inverse probability weighting to correct for the
overrepresentation of women from Poitiers. The cross-validated optimum
ENET tuning parameters were [alpha] = 0.49, [[lambda].sub.min] = 25.8
for birth weight; [alpha] = 0.48, [[lambda].sub.min] = 5.94 for
placental weight; and [alpha] = 0.55, [[lambda].sub.min] = 0.17 for
PFR. --, not applicable; BP3, benzophenone 3; BPA, bisphenol A; CI,
confidence interval; MBP, mono-n-butyl phthalate; MBzP, monobenzyl
phthalate; MCNP, monocarboxyisononyl phthalate; MCOP,
monocarboxyisooctyl phthalate; MCPP, mono(3-carboxypropyl) phthalate;
MEP, monoethyl phthalate; MiBP, mono-isobutyl phthalate; PFR,
placental-to-birth weight ratio; TCS, triclosan; [SIGMA]DCP, molar sum
of dichlorophenols; [SIGMA]DEHP, molar sum of MEHP, MEHHP, MEOHP and
MECPP; [SIGMA]PB, molar sum of parabens (methyl-, ethyl-, propyl- and
butylparaben).

(a) PFR = [placental weight(g)/birthweight(g)] x 100.
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Title Annotation:Research
Author:Philippat, Claire; Heude, Barbara; Botton, Jeremie; Alfaidy, Nadia; Calafat, Antonia M.; Slama, Remy
Publication:Environmental Health Perspectives
Article Type:Report
Date:Jan 1, 2019
Words:9135
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