Birth control pills are the most commonly used form of reversible birth control in the US. They are designed to prevent ovulation (and therefore pregnancy) and have a very low failure rate, which is part of the reason they are so widely used. However, there are cases where a woman does get pregnant while using or shortly after stopping use of an oral contraceptive, which might leave her wondering how the hormone-based medication will affect the embryo. Fortunately, there’s some good news from a recent study: researchers in Denmark found no increased risk of birth defects for women taking birth control pills shortly before getting pregnant or during early pregnancy.
The researchers looked at over 880,000 birth records for infants born between 1997 and 2011. After controlling for birth defects from known causes, they found that the rate of birth defects was consistent for women who had used birth control pills before getting pregnant, women who had used pills during early pregnancy, and women who had never used oral contraception at all. These findings were consistent with previous research that found no significant increase in birth defects due to birth control pill use.
The study should be reassuring to women who conceive shortly after they stop using oral birth control, or women who continue using this form of birth control before they find out they are pregnant. When used exactly as prescribed, the birth control pill failure rate is less than 1%, but the rate increases to about 9% for typical users, who may occasionally miss a pill or have the pill become less effective due to illness or medication interactions. This means that there is roughly a 9 in 100 chance that a woman will become pregnant while using birth control pills and may not realize it until she misses one or more periods.
Hypoplastic Left Heart Syndrome Diagram
Although the study didn’t find an increased risk for any subgroup of birth defects, the researchers were unable to rule out one rare defect called hypoplastic left heart syndrome. However, there were only three cases of this condition in the birth record sample, so more research is needed to determine if there is an association between the heart defect and birth control pill usage. The study authors also recommend additional research on different types of oral contraceptives, as they did not distinguish between different brands and generics when looking at birth records.
