Coffee does not increase pregnancy risks, genetic study suggests
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Coffee consumption during pregnancy was not linked to an increased risk for adverse outcomes, according to a study in the International Journal of Epidemiology.
“There have been some studies suggesting that coffee drinking during pregnancy could lead to an increase in the risk of miscarriage, stillbirths or preterm birth,” Gunn-Helen Moen, PhD, a fellow at the Institute for Molecular Bioscience at the University of Queensland, Australia, told Healio. “But many of these studies have been unable to test if coffee itself is actually causing these outcomes, as this observed association could be due to other factors. For instance, women who drink more coffee might sleep less, have more stressful jobs or have cigarettes with their coffee.”
Moen and colleagues conducted a two-sample Mendelian randomization (MR) study using data from the Coffee and Caffeine Genetics Consortium, which included 91,462 cases of coffee consumption. They used data from a large meta-analysis on miscarriages; data from the U.K. Biobank on stillbirths; data from the 23andMe cohort on gestational age and preterm birth; and data from the U.K. Biobank and the Early Growth Genetics Consortium on birth weight.
Additionally, the researchers conducted a one-sample genetic risk score analysis using data from the U.K. Biobank and the Avon Longitudinal Study of Parents and Children.
“Our study used genetic variants which we know are associated with how many cups of coffee an individual drinks per day,” Moen said. “We used these variants to see if there were any relationship between coffee drinking and the risk of miscarriage, stillbirth, preterm birth [and birth weight]. Because we used genetic variants, we were able to look at the effect of coffee drinking itself on these outcomes without the influences of other factors.”
Results of the two-sample MR analysis revealed that the genetic variants were not significantly associated with miscarriage, stillbirth, preterm birth and birth weight, meaning that coffee consumption did not increase the risk for these outcomes, according to Moen.
The one-sample genetic risk score analysis showed similar results.
Of note, both analyses linked drinking more coffee with higher birth weight, but the magnitude of the effect was inconsistent, according to the researchers.
“Our study didn't find any effect of coffee drinking on these outcomes, but I think it is important to note that we didn't look at a lot of other potentially interesting and relevant outcomes such as the child's neurodevelopment,” Moen said. “As caffeine is a neurostimulator, it could be that it would affect the baby in the womb, but we did not look into that in our study.”