Moderate daily caffeine intake during pregnancy may lead to
Pregnant women who consumed the caffeine equivalent of as little as half a cup of coffee a day on average had slightly smaller babies than pregnant women who did not consume caffeinated beverages, according to a study. The researchers found corresponding reductions in size and lean body mass for infants whose mothers consumed below 200 mg of caffeine per day, believed to increase risks to the fetus. Smaller birth size can place infants at higher risk of obesity, heart disease, and diabetes later in life.

A longitudinal cohort study, the National Institute of Child Health and Human Development Fetal Growth Studies–Singletons, enrolled 2055 nonsmoking women at low risk for fetal growth abnormalities with complete information on caffeine consumption from 12 US clinical sites between 2009 and 2013. Secondary analysis was completed in 2020.

Caffeine was evaluated by both plasma concentrations of caffeine and paraxanthine and self-reported caffeinated beverage consumption measured/reported at 10-13 weeks gestation.

A total of 2055 participants had a mean age of 28.3 years. Delivery occurred at a mean of 39.2 gestational weeks.

--Compared with the first quartile of plasma caffeine level, neonates of women in the fourth quartile had lower birth weight, length, and head, arm, and thigh circumference.

--Similar reductions were observed for paraxanthine quartiles, and for continuous measures of caffeine and paraxanthine concentrations.

--Compared with women who reported drinking no caffeinated beverages, women who consumed approximately 50 mg per day had neonates with lower birth weight, smaller arm and thigh circumference, and smaller anterior flank skin fold.

--Results did not differ by fast or slow caffeine metabolism genotype.

In this cohort study, small reductions in neonatal anthropometric measurements with increasing caffeine consumption were observed.