Alcohol

Pregnancy

CDC says alcohol can cross the placenta and affect fetal development; its guidance describes facial effects from first-trimester exposure and brain and growth problems from exposure at any point. AAP describes FASD as preventable birth defects and intellectual or neurodevelopmental disabilities. MotherToBaby says risk varies with amount, frequency, and other factors; daily and binge drinking are associated with higher FASD risk, while effects of smaller amounts are less certain. MotherToBaby describes one serving on one occasion as less likely to cause alcohol-related problems than heavy or binge use, without giving an individual probability. Miscarriage: Sundermann et al. (2019) reviewed 24 studies of 231,808 pregnant women and found an association between exposure and miscarriage (OR 1.19); among studies with up to five drinks per week, each additional weekly drink was associated with OR 1.06. Martinez Mayans et al. (2026) followed 3,225 women and partners; early-pregnancy intake below one glass per week and at least one glass per week was associated with higher miscarriage odds. Both results are observational and cannot establish cause or individual absolute risk. Other birth outcomes remain mixed: Aliyu et al. (2008; 655,979 singleton births) reported an observational stillbirth association; Sbrana et al. (2016; 1,370 women and newborns) found an adjusted association with low birth weight but not SGA or preterm birth; Weile et al. (2020; 15,776 pregnancies) found no higher spontaneous preterm birth with low average intake or binge episodes in early pregnancy. A 2026 benchmark-dose analysis of 2,227 participants across six cohorts found cognitive-outcome associations varied with both drinking frequency and dose per occasion; it is not an individual prediction or a threshold for a lower-risk amount.

Breastfeeding

LactMed reports that alcohol in milk closely follows blood levels and gives a 2 to 2.5 hour per drink interval after casual use. CDC gives a 2 hour per drink interval, says milk levels fall as blood alcohol falls, and states that pumping and discarding does not make alcohol leave milk faster. The CDC says moderate use of up to one standard drink in a day is not known to harm an infant, while more than one drink per day is not recommended. LactMed summarizes short-term studies in which feeding after one or two drinks can reduce infant milk intake and cause agitation or poor sleep. Mennella and Beauchamp (1991) studied 12 lactating women and infants; the infants consumed less milk in the alcohol condition than in the nonalcohol condition. MotherToBaby says longer-term child-development effects from alcohol in breast milk are not well studied and reports mixed findings; LactMed says long-term effects of daily use are unclear. CDC and LactMed describe reduced letdown or milk production with higher intake.

What was tested

Pregnancy evidence includes observational cohorts, case-control research, systematic reviews, and long-term child follow-up. Exposure was commonly self-reported, and differences in drinking patterns, pregnancy recognition, and other health and social factors limit causal conclusions. The 2026 cognitive analysis modeled average dose per drinking occasion together with drinking frequency across six longitudinal cohorts. The 2026 infant-movement study enrolled 625 infants, including 78 with alcohol-only exposure; it reported early movement findings but also high attrition and a need for replication. Breastfeeding evidence includes milk-level and pharmacokinetic studies and small short-term feeding or sleep studies. The 1991 infant-feeding study tested 12 lactating women and their infants after an alcohol or nonalcohol beverage; it does not establish long-term outcomes. The available evidence does not predict the result of an individual pregnancy or establish long-term effects from alcohol exposure through milk.