Link between Maternal Caffeine Consumption and Metabolism an
Higher caffeine consumption during pregnancy has been associated with lower birth weight. A Study was conducted to evaluate the association between maternal caffeine intake and neonatal anthropometry, testing effect modification by fast or slow caffeine metabolism genotype.

2055 nonsmoking women at low risk for fetal growth abnormalities with complete information on caffeine consumption from 12 US clinical sites were enrolled

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

--Compared with the first quartile of plasma caffeine level (less than 28 ng/mL), neonates of women in the fourth quartile (more than 659 ng/mL) had lower birth weight (beta =-84.3 g), length (beta =-0.44 cm), and head (beta = -0.28 cm), arm (beta =-0.25 cm), and thigh (beta = -0.29 cm) 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 (beta= -66 g), smaller arm (beta = -0.17 cm) and thigh (beta = -0.32 cm) circumference, and smaller anterior flank skin fold (beta= -0.24 mm).

In conclusion, rising caffeine intake resulted in minor reductions in neonatal anthropometric measurements. The findings indicate that caffeine intake during pregnancy, also at levels well below the recommended 200 mg per day, is linked to fetal growth reduction.