The study suggests that women's genes have a huge influence on why they get pregnant while on the pill.
There are many reasons why some women choose to go on the pill. Extreme pain during menstrual cramps, discomfort, not wanting to risk pregnancy, and lifestyle discomfort are among some of them. However, there are many cases where women have ended up getting pregnant while they were on the pill. Most times when this happens, doctors assume that the women weren't taking the contraceptive the right way because it was thought to be impossible or such a thing to happen. Scientists recently found out that, in some cases where women were following the procedure as they were told to, their genes might have something to do with the pregnancy. The study that was published on March 12, suggests that a woman's genes put her at the risk of getting pregnant while she is using the hormonal birth control pill properly. According to the researchers at the University of Colorado Anschutz Medical Campus, the CYP3A7 gene breaks down the hormones that are commonly found in contraceptives. "The findings mark the first time a genetic variant has been associated with birth control," said the study's lead author Aaron Lazorwitz, M.D., assistant professor of Obstetrics and Gynecology at the University of Colorado School of Medicine.
The study found that some women possess the relatively rare version of a gene which is known as CYP3A7. While these women are on hormonal birth control, they tend to have lower blood levels of the hormones needed for the birth control to work as compared to most other women who possess the common versions of the gene. Researchers say that the gene codes for liver enzymes and is usually seen to be active in fetuses and is switched off before birth. However, the gene is said to stay active in some people and it results in a faster breakdown of the hormones present in birth control.
The hormones commonly found in the contraceptives that are easily broken down by the gene are estrogen and progestin. The research suggests that the faster breakdown caused by the gene increases the risk of pregnancy, especially if the women are using low-dose hormonal contraception. "When a woman says she got pregnant while on birth control, the assumption was always that it was somehow her fault," said Dr. Lazorwitz. "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]."
While the study has made suggests that the gene is responsible for unplanned pregnancies while on the pill, researchers say that more research is needed to confirm the results. They also mentioned that other genes might also have a part to play in increasing the risk of hormonal birth control to fail. If further studies suggest that this is the main or only gene responsible then doctors might one day consider genetically testing women for these genes if they become pregnant while on birth control. Hormonal birth control pills are the most commonly prescribed pills in the U.S.
The pills need to be used exactly as directed for them to work. If this is done, birth control pills are about 99 percent effective at preventing pregnancy, according to Planned Parenthood. Research shows that 9 out of 100 women who are on birth control end up getting pregnant every year. However, in most cases, the reason behind the unplanned pregnancy is believed to be missed pills. In the new study, the researchers looked at data from 350 healthy women, average age of 22 years, who had a contraceptive implant inserted into their arms for at least one year. The device is said to steadily release a dose of the hormone progestin to prevent pregnancy.
The reason women with the implant were chosen for the study was that researchers wanted to only study women who were getting a constant dose of the hormone. This way they ruled out any possibility of any of the subjects not getting the right dose because of forgetting to take a pill. The authors found that about 5 percent of participants (18 women) had a variant of the CYP3A7 gene known as CYP3A7*1C and had levels of the hormonal medication in their blood that were, on average, 23 percent lower than participants with a more common gene variant.
In addition, among the 18 people with CYP3A7*1C, five (28 percent) showed that the level of medication in their blood was slightly lower than they needed for the contraceptive to work efficiently. Researchers suggest that the findings also apply to those women who use the hormonal birth control since the hormones that are produced by the implants and the pill are the same. They are even broken down in similar ways, according to Dr. Lazorwitz. However, future studies will be conducted in order to prove this.
"At this point, it is too early to say that CYP3A7*1C carriers have a certain risk of contraceptive failure, as [more research] is needed to really quantify what that risk may be," Dr. Lazorwitz told Live Science. He further added in the study, "As more genetic data becomes available, clinicians may need to consider adding genetic predisposition to increased steroid hormone metabolism in their differential diagnosis for unintended pregnancies in women reporting perfect adherence to hormonal contraceptive methods."