Researchers from the National Institutes of Health and Ohio State University report that the risk of miscarriage increases if couples consume over two caffeinated beverages a day in the weeks leading up to conception. Findings from their study are published in Fertility and Sterility.

The study authors also found that women who consumed over two daily caffeinated beverages during the first seven weeks of pregnancy were also more likely to miscarry. Taking a daily multivitamin, however, reduced the likelihood of miscarriage in women compared to those who did not take a multivitamin.

Germain Buck Louis, PhD, the study’s primary author, and colleagues analyzed data from the LIFE (Longitudinal Investigation of Fertility and the Environment) Study that evaluated the association between fertility, lifestyle, and environmental chemical exposure. A total of 501 couples from Michigan and Texas were enrolled between 2005–2009.

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For the analysis, the team of researchers compared factors such as cigarette use, caffeinated beverage consumption and multivitamin use among 344 couples with a singleton pregnancy from the weeks prior to conception through Week 7 of pregnancy.

The data showed 98 of the 344 pregnancies resulted in miscarriage (28%). The risk of miscarriage was almost double in older women (aged ≥35 years) than younger women (hazard ratio [HR] 1.96). The increased risk may be attributed to advanced age of the sperm and egg in older couples or cumulative exposure to substances in the environment.

Couples who consumed more than two caffeinated beverages daily were also at increased risk (HR 1.74 [females] and HR 1.73 [males]). Dr. Louis pointed out that the current study findings suggest caffeinated beverage consumption during the study period directly contributed to miscarriage whereas previous studies “could not rule out whether caffeine consumption contributed to pregnancy loss or was a sign of an unhealthy pregnancy.”

In addition, women who took a daily multivitamin had a reduced risk of miscarriage (HR 0.45). Those who continued taking multivitamins through early pregnancy saw a further reduction in risk (HR 0.21). The study authors explained the reduced risk may come from vitamin B6 and folic acid found in prenatal vitamins.

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