Shunning caffeine during the second half of pregnancy has no effect on the baby’s weight or on the likelihood of premature birth, according to a Danish study.
Caffeine is known to pass easily into the fetus’s bloodstream, and some researchers think it may reduce the growth of the fetus by constricting blood vessels and reducing the supply of oxygen.
But Dr. Bodil Bech and coworkers at the University of Aarhus in Denmark found that reducing caffeine intake after 20 weeks of pregnancy, when the most fetal growth takes place, has no effect on birth weight or the length of the pregnancy.
The researchers recruited more than 1,200 women before the twentieth week of pregnancy, all of whom drank at least three cups of coffee per day. Participants were randomly assigned to switch to an unlabelled supply of instant coffee that was either caffeinated or decaffeinated, and were interviewed throughout their pregnancies about their caffeine intake from other sources, such as tea and cola.
There were no differences in birth weight or length of pregnancy between groups of women who drank caffeinated or decaffeinated coffee.