This study estimates the effect of maternal caffeine consumption throughout pregnancy on fetal growth. We studied 2,714 women who delivered a liveborn infant between 1988 and 1991. Detailed information regarding coffee, tea, and soda drinking during the first and third trimesters of pregnancy was obtained. Average caffeine intake during month 1 of pregnancy was higher than for month 7 (72.4 vs 54.0 mg per day). Consumption of >300 mg caffeine per day during month 1 (adjusted odds ratio = 0.91; 95% confidence interval = 0.44--1.90) and during month 7 (adjusted odds ratio = 1.00; 95% confidence interval = 0.37--2.70) was not associated with intrauterine growth retardation. There was little evidence for any effect modification due to cigarette smoking on the caffeine associations. This study provides evidence that antenatal caffeine consumption has no adverse effect on fetal growth.