In the linked cohort study (doi:10.1136/bmj.a2332), the CARE Study Group reports that consuming caffeine during pregnancy is associated with an increased risk of fetal growth restriction.1 For 100-199 mg caffeine a day the odds ratio was 1.2 (95% confidence interval, 0.9 to 1.6), for 200-299 mg a day it was 1.4 (1.0 to 2.0), and for over 300 mg a day it was 1.5 (1.1 to 2.1).

Coffee and tea contain a variety of chemical compounds, but most of the health concerns relate to caffeine. One cup of coffee contains about 100 mg of caffeine and a cup of tea about half of this amount; the exact amount varies according to cup size, brewing methods, and brands of coffee or tea.2 Caffeine is also present in cola, chocolate, cocoa, and some drugs. Most of the caffeine that adults consume comes from coffee,3 but in the present study 60% of the caffeine that pregnant …