A new genetic study suggests drinking coffee during pregnancy does not negatively affect birthweight, nor does it increase the risk of a miscarriage, stillbirth, or premature birth.
The study, by researchers at the University of Queensland in Australia and the University of Oslo, counters the advice often given during pregnancy to avoid caffeine. That advice was based on observational studies that did not separate coffee drinking from the harmful effects of behaviors like smoking, drinking alcohol, or poor nutrition.
But in this study the researchers focused solely on the effects of drinking coffee.
They used data from several sources, including UK Biobank and from 23andMe customers who consented to participate in research. Ideally, the researchers would have isolated the effects of drinking coffee by doing a randomized trial. This would have required recruiting a very large group of pregnant women and then requiring some to drink coffee, and the others would not be allowed to drink coffee. Then researchers would monitor the effect on their pregnancies. For several reasons, that study design is not feasible in this case. So instead, the researchers used Mendelian randomization to mimic a randomized trial. They did this by first looking at genetic variants associated with drinking coffee and then seeing if they also affect pregnancy outcomes.
Using this genetic analysis, the researchers found no causation between drinking coffee during pregnancy and pregnancy risks for miscarriage, stillbirth, or premature birth.
At the same time, the study only looked at a handful of adverse pregnancy outcomes, leaving the possibility that drinking coffee could affect other aspects of a baby’s development.
“For that reason, we don’t recommend a high intake during pregnancy, but a low or moderate consumption of coffee,” said Dr. Gunn-Helen Moen, a lead researcher for the study.
This research used genetic data from the Coffee and Caffeine Genetics Consortium, the UK Biobank, the Avon Longitudinal Study of Parents and Children, and customers from 23andMe who consented to participate in research.
The study was published in the International Journal of Epidemiology.