Caffeine raises risk of miscarriage but multivitamins lower it, study finds

Both the mother’s and the father’s caffeine consumption affects a couple’s chances to miscarry—more than 2 cups a day in the weeks before conception raises risk of pregnancy loss by more than 70%, according to a National Institutes of Health-sponsored study published online March 22, 2016 in the journal Fertility and Sterility.

However, women who took a daily multivitamin in the weeks before conception reduced their risk of miscarriage by more than half, the researchers found.

“Our findings provide useful information for couples who are planning a pregnancy and who would like to minimize their risk for early pregnancy loss,” said the study’s first author Germaine Buck Louis, PhD, Director of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, in Rockville, MD.

For this study, the researchers followed 344 couples with a singleton pregnancy from the weeks before they conceived through the seventh week of pregnancy. The couples recorded their daily use of cigarettes, caffeinated and alcoholic beverages, and multivitamins.

Of the 344 pregnancies, 98 (28%) ended in miscarriage (which is comparable to the percentage of pregnancy loss found in other studies). The researchers weren’t surprised to find that the mother’s age was a factor. However, they observed a particular “threshold effect” starting at age 35—women this age and older had nearly twice the risk of miscarriage as younger women.

Notably, the researchers also found that drinking 2 or more caffeinated beverages every day increased pregnancy loss. “Our findings also indicate that the male partner matters, too,” said Dr. Buck Louis. “Male preconception consumption of caffeinated beverages was just as strongly associated with pregnancy loss as females’”—with a comparable hazard ratio in both parents: 1.74 for females and 1.73 for males.

The researchers didn’t ask participants about consumption of decaffeinated or caffeine-free drinks, so they can’t say whether these could be a safe alternative to caffeinated beverages. More research is needed to investigate that, they said.

In addition, the researchers asked about multivitamin intake, including either over-the-counter multivitamins or prescribed prenatal vitamins. They found that women who took a daily multivitamin before conception dramatically reduced their risk of pregnancy loss by 55%. This increased to a 79% reduction risk for women who continued to take the vitamins through early pregnancy.

In summary, “couples might continue to be advised that advanced age increases the risk of pregnancy loss and to limit caffeinated intake to fewer than 3 daily beverages irrespective of source and that women should continue to take daily multivitamins before and during pregnancy consistent with clinical guidance,” the authors concluded.