Prospective Study of Maternal Alcohol Intake During Pregnancy or Lactation and Risk of Childhood Asthma: The Norwegian Mother and Child Cohort Study

Abstract

Many women drink during pregnancy and lactation despite recommendations to abstain. In animals, alcohol exposure during pregnancy and lactation influences lung and immune development, plausibly increasing risk of asthma and lower respiratory tract infections (LRTIs). Studies in humans are few. In the Norwegian Mother and Child Cohort Study, we examined maternal alcohol intake during pregnancy and lactation in relation to risk of current asthma at 36 months (49,138 children), recurrent LRTIs by 36 months (39,791 children), and current asthma at 7 years (13,253 children). Mothers reported frequency and amount of alcohol intake each trimester and the first 3 months following delivery. We calculated adjusted relative risk (aRR), comparing children of drinkers to nondrinkers, using Generalized Linear Models. A total of 31.8% of mothers consumed alcohol during first trimester, 9.7% during second trimester, and 15.6% during third trimester. Infrequent and low-dose prenatal alcohol exposure showed a modest statistically significant inverse association with current asthma at 36 months (aRRs ~ 0.85). No association was seen with the highest alcohol intakes during the first trimester when alcohol consumption was most common. RRs of maternal alcohol intake during pregnancy with recurrent LRTIs were ~1, with sporadic differences in risk for some metrics of intake, but without any consistent pattern. For current asthma at 7 years, similar inverse associations were seen as with current asthma at 36 months but were not statistically significant. Among children breastfed throughout the first 3 months of life, maternal alcohol intake during this time was not significantly associated with any of the 3 outcomes. The low levels of alcohol exposure during pregnancy or lactation observed in this cohort were not associated with increased risk of asthma or recurrent LRTIs. The slight inverse associations of infrequent or low-dose prenatal alcohol exposure with asthma may not be causal.