Alcohol and lactation: do no harm.

To the Editor: In the not-so-distant past, leading experts claimed that drinking alcohol during lactation, as well as during pregnancy, was 'safe'. (1,2) More than being deemed safe, drinking was actually encouraged as the lore of many cultures claimed that alcohol optimised the process of lactation. Drinking small quantities of alcohol shortly before nursing was, and continues to be, believed by some to increase milk yield, facilitate milk let-down and relax both mothers and infants. (1) Recent scientific findings call these practices into serious question, however.

Giglia and Binns systematically reviewed the current scientific literature on alcohol and lactation, some of which was conducted in my laboratory, in a previous issue of Nutrition & Dietetics (Volume 63). (3) Contrary to popular lore, our research revealed that infants, whose ages ranged from <1 to 7 months, ingested less milk at the breast and their sleep was disrupted during the hours immediately following the consumption of the equivalent of 1.5 Australian standard drinks by their mothers. (4-7) The diminished intake was due to alcohol-induced decreases in milk production (8) and disruption in the key hormones underlying lactational performance. (9)

In the longer term, infants who were exposed regularly (at least daily) to alcohol in their mothers' milk exhibited a slight, but significant, deficit in gross motor development. (10) The deficits in motor functioning were the result of alcohol exposure and not secondary to alcohol-induced alterations in maternal behaviour because infants whose mothers drank heavily but weaned their infants early, had significantly higher scores on motor development than those who were weaned at an older age. (11) Beyond alcohol's effects on the breastfed infants and its disruptive effects on the lactational process, a growing body of experimental research in animal models and humans suggests that experiences with flavours in mother's milk, (12) including alcohol, bias the infants' behaviours and preferences during infancy, childhood and adolescence. (1,13-15) For example, the more women drank during lactation (all of whom did not drink alcohol daily), the more their infants orally explored an alcohol-scented toy. (14) Moreover, children learn to associate the odour of ethanol within the context of their mothers and the effects that alcohol has on her behaviours. (16)

Based on this and other scientific evidence reviewed by Giglia and Binns, (3) drinking one to two standard drinks daily during lactation may actually be counterproductive. As I have written in the past, although mothers may be more relaxed after a drink, the hormonal milieu underlying lactation is altered and their infants' feeding and sleep behaviours are disrupted in the short term and motor development in the long term. (1,9) Given such conclusions, which the authors restated in their review, it is quite perplexing and alarming that they then advise that drinking one to two standard drinks per day, when the child is one month of age or older, is 'conducive to the optimal development of their young infant while supporting successful breastfeeding (Table 5)'. Such statements are not supported by their scientific review as the research demonstrating alcohol-induced disruptions in infants' behaviours and lactational performance focused on infants, the majority of whom were older than one month of age, and the dosages of alcohol demonstrating such disruptions were within the authors' range of preferred number of drinks. Moreover, the recommendation that mothers should drink after breastfeeding fails to recognise that what is important is how much time has elapsed between drinking and breastfeeding. If an infant is breastfeeding every hour, then they will be exposed to maximal amounts of alcohol in milk if mothers follow their advice.

By advising lactating women to limit alcohol intake to one to two standard drinks per day, Giglia and Binns, like many others have in the past, deemed that daily consumption of such amounts is safe during lactation. (3) Based on the science they so elegantly reviewed, such recommendations could do harm.

Julie A. Mennella, PhD

Member and Director of Education Outreach, Monell Chemical Senses Center Philadelphia, Pennsylvania, USA

REFERENCES

1 Mennella JA. The transfer of alcohol to human milk: sensory implications and effects on mother-infant interaction. In: Hannigan JH, Spear N, Spear L, Goodlett CR, eds. Alcohol and Alcoholism: Brain and Development. Mahwah, NJ: Lawrence Erlbaum Associates, Inc., 1999; 177-98.

2 Golden J. Message in a Bottle: The Making of Fetal Alcohol Syndrome. Cambridge, MA: Harvard University Press, 2005; 16-34.

3 Giglia R, Binns C. Alcohol and lactation: a systematic review. Nutr Diet 2006; 63: 103-16.

4 Mennella JA, Beauchamp GK. The transfer of alcohol to human milk. Effects on flavor and the infant's behavior. N Engl J Med 1991; 325: 981-5.

5 Mennella JA, Beauchamp GK. Beer, breast feeding, and folklore. Dev Psychobiol 1993; 26: 459-66.

6 Mennella JA, Garcia-Gomez PL. Sleep disturbances after acute exposure to alcohol in mothers' milk. Alcohol 2001; 25: 153-8.

7 Mennella JA, Gerrish CJ. Effects of exposure to alcohol in mother's milk on infant sleep. Pediatrics 1998; 101: e21-5.

8 Mennella JA. Regulation of milk intake after exposure to alcohol in mothers' milk. Alcohol Clin Exp Res 2001; 25: 590-93.

9 Mennella JA, Pepino MY, Teff KL. Acute alcohol consumption disrupts the hormonal milieu of lactating women. J Clin Endocrinol Metab 2005; 90: 1979-85.

10 Little RE, Anderson KW, Ervin CH, Worthington-Roberts B, Clarren SK. Maternal alcohol use during breast-feeding and infant mental and motor development at one year. N Engl J Med 1989; 321: 425-30.

11 Little RE. Maternal use of alcohol and breast-fed infants--Reply. N Engl J Med 1990; 322: 339.

12 Mennella JA, Jagnow CP, Beauchamp GK. Prenatal and postnatal flavor learning by human infants. Pediatrics 2001; 107: E88.

13 Mennella JA. Infants' suckling responses to the flavor of alcohol in mothers' milk. Alcohol Clin Exp Res 1997; 21: 581-5.

14 Mennella JA, Beauchamp GK. Infants' exploration of scented toys: effects of prior experiences. Chem Senses 1998; 23: 11-17.

15 Spear NE, Molina JC. Fetal or infantile exposure to ethanol promotes ethanol ingestion in adolescence and adulthood: a theoretical review. Alcohol Clin Exp Res 2005; 29: 909-29.

16 Mennella JA, Garcia PL. Children's hedonic response to the smell of alcohol: effects of parental drinking habits. Alcohol Clin Exp Res 2000; 24: 1167-71.