- If a woman gets pregnant while on contraception, it’s usually assumed she hasn’t been taking it properly.
- But according to new research, this may not be true, and a certain gene may affect how the hormones are broken down in the body.
- The study from the University of Colorado Anschutz Medical Campus looked at data from 350 women, and found that 5% of them had a gene still active which is usually switched off at birth.
- This gene makes a particular enzyme that breaks down the hormones in contraceptives, like estrogen and progestin.
- “These findings show that we should listen to our patients and consider if there is something in their genes that caused this [unplanned pregnancy,]” said lead author Aaron Lazorwitz.
Despite taking the contraceptive pill, about 9 out of 100 women get pregnant every year. This is often considered to be a result of them taking it incorrectly — missing pills or not taking them at the same time every day. But according to a new study, published in the journal Obstetrics & Gynecology, your genes could mean it’s beyond your control.
Researchers at the University of Colorado Anschutz Medical Campus looked at data from 350 healthy women, with an average age of 22, who had a contraceptive implant inserted for anywhere between 12 and 36 months. The implant releases a steady dose of progestin, which is a hormone that prevents pregnancy.
Women with implants were chosen for the study to minimise the chance of an ineffective hormone dose, which is a risk with the contraceptive pill if it’s taken incorrectly.
The team tested the women for a gene called CYP3A7*1C, which makes a particular enzyme that breaks down the hormones in contraceptives, like estrogen and progestin. It’s usually switched off at birth, but for around 5% of the women in the study it was still making the enzyme in adulthood.
“That enzyme breaks down the hormones in birth control and may put women at a higher risk of pregnancy while using contraceptives, especially lower dose methods,” said Aaron Lazorwitz, an assistant professor of obstetrics and gynecology and lead author of the study.
“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 [unplanned pregnancy.]”
The researchers note that further studies are needed to confirm whether the presence of this active gene does increase the chance of accidental pregnancy. Also, while hormones in the implant and in oral contraceptives are broken down in similar ways in the body, there may be slight differences that affect the results for women who take the pill.
But if further research does confirm the theory, Lazorwitz said this could lead to developing more precise contraceptive treatments for individual patients. It could also help with the problem of side effects varying from woman to woman, Anne Davis, an obstetrician-gynecologist, told New York Post.
“One woman will say I took this medication and I feel lousy, another will say it works great, I’m not pregnant; my periods are easier; and my skin has cleared up,” she said.
“Knowing that there is a difference in how people metabolize hormones sets the stage for more research that can help us understand the experiences of women better and that can help us give the right medication to the right patient.”