The effects of maternal alcohol (ethanol) ingestion during lactation are complex and depend on the pattern of maternal drinking. Alcohol decreases milk production, with 5 drinks or more decreasing milk letdown and disrupting nursing until maternal alcohol levels decrease. Beer may increase serum prolactin levels during nursing because of polysaccharides from barley and hops. After ingestion of nonalcoholic beer, the antioxidant capacity of milk is increased, but alcohol levels in milk are negligible. In a US survey, of 102 mothers who used beer as a galactogogue 42% thought it increased milk supply.[1] Women with a family history of alcoholism have a blunted prolactin response following breast stimulation and tend to breastfeed more frequently to compensate.
Breastmilk alcohol levels closely parallel blood alcohol levels. The highest alcohol levels in milk occur 30 to 60 minutes after an alcoholic beverage, but food delays the time of peak milk alcohol levels. Nursing after 1 or 2 drinks (including beer) can decrease the infant's milk intake by 20 to 23% and cause infant agitation and poor sleep patterns. Nursing or pumping within 1 hour before ingesting alcohol may slightly reduce the subsequent amounts of alcohol in breastmilk.
In infants who were subjected to high alcohol exposure during pregnancy, breastfeeding for 4 or more months improved markedly on Bayley scales of mental and psychomotor development compared to infants who were breastfed 3 months or less.[2] Casual use of alcohol (such as 1 glass of wine or beer per day) is unlikely to cause either short- or long-term problems in the nursing infant,[3] especially if the mother waits 2 to 2.5 hours per drink before nursing, and does not appear to affect breastfeeding duration. Daily heavy use of alcohol (more than 2 drinks daily) appears to decrease the length of time that mothers breastfeed their infants. The long-term effects of daily use of alcohol on the infant are unclear. Some evidence indicates that infant growth and motor function may be negatively affected by 1 drink or more daily, but other studies have not confirmed these findings. Heavy maternal use may cause excessive sedation, fluid retention, and hormone imbalances in breastfed infants. Greater or riskier alcohol consumption by nursing mothers may affect their children’s academic performance negatively in school. Preliminary data failed to find an increased risk of autism spectrum disorder or attention deficit hyperactivity disorder among the infants whose mothers used alcohol during breastfeeding.[4] The use of alcohol-based hand sanitizers do not appear to result in clinically relevant alcohol levels in breastmilk.[5]