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More adverse outcomes in severe sleep apnea.

MINNEAPOLIS -- Women with sleep-disordered breathing have an increased likelihood of adverse pregnancy outcomes, but it is unclear whether the heightened risk can be attributed primarily to the breathing disorder or to obesity reported lead investigator Dr. Francesca L. Facco.

Sleep disordered breathing (SDB) occurs in approximately 2% of the female population and has been linked to cardiovascular and metabolic morbidities and mortality in nonpregnant populations, said Dr. Facco of the department of ob.gyn. at Northwestern University in Chicago. "There is some evidence that pregnancy may precipitate or exacerbate the condition, and that there may be a relationship between intrauterine fetal growth retardation and maternal preeclampsia." Unfortunately, "few studies have examined the relationship between abnormal respiratory patterns or quality of ventilation during sleep in pregnancy and adverse obstetrical outcomes, which is what we sought to do in this investigation" she said at the meeting.

Toward this end, Dr. Facco and her colleagues conducted a retrospective cohort study, using ICD-9 codes to identify women who had a delivery and an in-laboratory polysomnogram at their institution between January 2000 and June 2009. They reviewed the medical charts of 150 patients and abstracted data on demographics, sleep study results, and pregnancy outcomes. "In women with more than one pregnancy, we looked at the first pregnancy with outcome information," she explained.

The study's primary outcome was adverse pregnancy outcome, which was defined as pregnancy-induced hypertension, gestational diabetes, and early preterm birth (at or before 34 weeks' gestation), Dr. Facco said.

The apnea-hypopnea index (AHI) was used to classify the presence and degree of SDB, with an AHI of fewer than 5 breathing pauses per hour indicating no SDB, an AHI of 5-14.9 pauses per hour indicating mild to moderate SDB, and an AHI of 15 or more pauses per hour suggesting a severe condition, she said. The associations between SBD and adverse pregnancy outcomes were evaluated using a Chi-square test for trend.

Of the 150 women included in the investigation, 61% were nulliparous at the time of their first documented delivery at the study hospital, 72% had undergone a polysomnogram within 3 years of their delivery, and 86.7% were overweight or obese (defined as a body mass index of 25 kg/[m.sup.2] or greater) at the time of delivery Dr. Facco reported.

An analysis of the findings demonstrated a significant association between SDB and adverse pregnancy outcome.

"The incidence of adverse pregnancy outcomes was highest in women with severe sleep apnea," she said, noting that the increased prevalence was principally driven by a higher incidence of gestational diabetes and early preterm birth.

In the no, mild, and moderate to severe SDB groups, respectively, researchers found the following:

* The composite adverse pregnancy outcome rates were 18.1%, 23.5%, and 38.5%.

* The gestational diabetes rates were 0%, 5.9%, and 11.5%.

* The preterm birth rates were 4.7%, 5.9%, and 15.4%.

* The pregnancy-induced hypertension rates were 16.9%, 17.6%, and 15.4%.

"Gestational diabetes has been independently associated with maternal obesity, as has preterm birth and low birth weight," Dr. Facco said in an interview. "In this population, nearly 87% of the women who had [SDB] were also obese, making it an obvious confounding factor."

Further prospective studies are needed to assess the independent impact of SDB on maternal and neonatal health, and if the independent association is confirmed, additional studies on the role of treatment in pregnancy would be needed, Dr. Facco said.


Major Finding: In the no, mild, and moderate to severe sleep disordered breathing groups, the composite adverse pregnancy outcome rates were 18.1%, 23.5%, and 38.5%, respectively.

Data Source: A retrospective cohort study to assess the association between sleep-disordered breathing and adverse pregnancy outcomes in150 women who had a delivery and an in-laboratory polysomnogram between January 2000 and June 2009.

Disclosures: Dr. Facco said she had no relevant financial disclosures.


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Title Annotation:OBSTETRICS
Author:Mahoney, Diana
Publication:OB GYN News
Date:Sep 1, 2011
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