Caffeine and pregnancy

Today’s papers report that ‘just two cups of coffee per day can double the risk of miscarriage’, following the publication of a study in the American Journal of Obstetrics & Gynecology. The researchers observed 1,063 pregnant women and found that those who had 200mg or more of caffeine per day (two or more cups of coffee per day) had twice the miscarriage risk of women who had no caffeine.

The Food Standards Agency's current advice to pregnant women, issued in 2001, is to keep their caffeine intake to less than 300 mg per day. This is about three mugs of instant coffee, but it’s really important for women to be aware that they must also think about caffeine they’ve had from all sources, including soft drinks, food and medication.

This advice was based on the opinion of the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT), which looked at the data on reproductive effects of caffeine that was available at this time.

The COT noted a number of uncertainties in the available data and in response the Food Standards Agency has funded a study, involving around 2,500 pregnant women. This study aims to address some of these uncertainties and help the FSA give the best possible advice to pregnant women. Our study looks at caffeine intake from all sources, including medication, and considers the birth outcomes of the women. People vary widely in their ability to clear caffeine from their bodies, and this may or may not influence effects during pregnancy. Our study is looking at this and women have been characterised as either ‘fast’ or ‘slow’ caffeine metabolisers. This study will soon be complete.

At their last meeting, in December 2007, the COT reviewed an update of relevant research on reproductive effects of caffeine. When we have the committee's views on the literature update, this new study by Weng et al and the results of the FSA-funded research, the FSA will decide whether it needs to amend its current advice on caffeine consumption in pregnancy.