As much as we might try to plan our families, as Bob Ross would say, sometimes a “happy little accident” can happen. If a happy accident has happened to you or someone you know, human error isn’t necessarily at fault. New research published in the journal Obstetrics & Gynecology may have found a reason for why birth control fails for some women.

Researchers at the University of Colorado Anschutz Medical Campus studied 350 women who had had a contraceptive implant in place for 12 to 36 months. Five percent of the participants had a gene called CYP3A7*1C—and it’s that gene that put women at greater risk for hormonal birth control failure, according to the researchers.

photo: ecooper99 via Flickr

So what does a gene have to do with unintended pregnancy? The CYP3A7*1C is typically only active in fetuses. After birth the gene switches off—or at least it should. If the gene, which manufacturers the CYP3A7 enzyme, continues to work after birth, it can contribute to the breakdown of the hormones used in some birth control methods.

So what does this mean for you? In theory, if you have the gene in question, your hormonal birth control could fail. But unless you have a full genetic workup, it’s not likely you’ll ever know you have an active CYP3A7*1C. The research is a starting step towards a better understanding of the influence our genes have on what we put into our bodies.

According to the study’s lead author, Aaron Lazorwitz, MD, assistant professor of Obstetrics and Gynecology at the University of Colorado School of Medicine, “When a woman says she got pregnant while on birth control the assumption was always that it was somehow her fault. But these findings show that we should listen to our patients and consider if there is something in their genes that caused this.”

—Erica Loop



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