Clinical Inquiry: Does caffeine intake during pregnancy affect birth weight?

No. Reducing caffeinated coffee consumption by 180 mg of caffeine (the equivalent of 2 cups) per day after 16 weeks' gestation doesn't affect birth weight. Consuming more than 300 mg of caffeine per day is associated with a clinically trivial, and statistically insignificant (less than 1 ounce), reduction in birth weight, compared with consuming no caffeine.