Does alcohol affect birth outcomes?

A study by researchers from Yale University and Brown University suggests that low-to-moderate alcohol consumption during pregnancy may not increase risk of birth outcomes such as low birthweight. The findings, from an epidemiologic study, were published in the Annals of Epidemiology and reflect associations, not direct cause and effect.

Researchers used multivariate analysis to estimate whether low-to-moderate prenatal alcohol exposure was associated with selected birth outcomes in a cohort of 4,496 women with singleton infants. The outcomes evaluated were low birthweight, preterm delivery, intrauterine growth restriction (IUGR), and selected perinatal outcomes.

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Odds of low birthweight and of birth length less than 10^th percentile were reduced in offspring of women who drank in early pregnancy (OR 0.66; 95% CI, 0.46-0.96 and OR 0.75; 95% CI, 0.56-0.97, respectively). Reduced odds of birth length and head circumferences less than 10^th percentile were associated with drinking during the first trimester (OR 0.56; 95% CI, 0.36-0.87 and OR 0.69; 95% CI, 0.50-0.96, respectively). Drinking during the third trimester was associated with lower odds of low birthweight and preterm delivery (OR 0.56; 95% CI, 0.34-0.94 and OR 0.60; 95% CI, 0.42-0.87, respectively).

The researchers concluded that low-to-moderate alcohol exposure during early and late gestation is not associated with increased risk of low birthweight, preterm delivery, IUGR, and most selected perinatal outcomes.    

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