The transfer of alcohol to human milk: Effects on flavor and the infant's behavior

Background. The amount of alcohol ingested by a breast-fed infant is only a small fraction of that consumed by its mother, but even this small amount may have an effect on the infant. We investigated whether the ingestion of alcohol by a lactating woman altered the odor of her milk and whether exposure to a small amount of alcohol in the mother's milk had immediate effects on the behavior of the infant. Methods. Twelve lactating women and their infants were tested on two days separated by an interval of one week. On each testing day, the mother expressed a small quantity of breast milk and then drank either orange juice or orange juice containing a small quantity of ethanol (0.3 g per kilogram of body weight). Additional milk samples were obtained at fixed intervals after the ingestion of the beverage and analyzed to determine their ethanol content. The samples were also evaluated by a panel of adults to determine whether any difference in the odor of the milk was detectable after alcohol ingestion. The infants were weighed before and after nursing to assess the amount of milk they ingested, and their behavior during breast-feeding was monitored by videotape. Results. Short-term alcohol consumption by lactating women significantly and uniformly increased the perceived intensity of the odor of their milk as assessed by the panel; this increase in the intensity of the odor peaked 30 minutes to 1 hour after the alcohol was consumed and decreased thereafter. The alteration in the odor of the milk closely paralleled the changes in the concentration of ethanol in the milk (mean range, 0 to 6.9 mmol per liter [0 to 32 mg per deciliter]). The infants sucked more frequently during the first minute of feedings after their mothers had consumed alcohol (67.0 +/- 6.5 sucks, as compared with 58.4 +/- 5.9 sucks for feedings after the consumption of the nonalcoholic beverage; P<0.05), but they consumed significantly less milk (120.4 +/- 9.5 ml vs. 156.4 +/- 8.2 ml, P<0.001) during the testing sessions in which their mothers drank the alcoholic beverage. Conclusions. Although the mechanisms underlying this reduction in milk intake remain to be elucidated, this study shows that short-term alcohol consumption by nursing mothers has an immediate effect on the sensory characteristics (odor) of their milk and the feeding behavior of their infants.