Drinking tea or coffee during pregnancy reduces baby size

New research suggests women who drink coffee or tea during pregnancy will have smaller babies.

Even women who drink less than the ‘safe’ cutoff of 200mg caffeine – about two mugs of instant coffee or three cups of tea – are more at risk of having low-birth weight or premature newborns.

The researchers, from University College Dublin, believe caffeine restricts blood flow to the placenta, affecting babies’ growth.

The study, led by doctor Ling-Wei Chen, looked at 941 mother-child pairs born in Ireland. Tea was the mothers’ main source of caffeine (48 per cent), followed by coffee (38 percent).

Dr Chen told Reuters:

Based on the consistent associations we observed, and because many pregnancies are unplanned, we would recommend women who are pregnant or seeking to become pregnant at least limit their intakes of caffeinated coffee and tea.
High caffeine intake can result in restricted blood flow in the placenta which may subsequently affect fetal growth.
Caffeine can also cross the placenta readily, and because caffeine clearance slows as pregnancy progresses, caffeine accumulation may occur in fetal tissues.