Analyzing Genetics May Lead to Better Contraceptive Experiences for Women

Women using hormonal birth control can experience a variety of side effects, including weight gain, irregular bleeding, mood swings, acne, headaches, cramping, and even contraceptive failures leading to unintended pregnancies, in rare cases. Because everyone reacts differently to different forms of hormonal birth control, it can be difficult to determine which method will work best for an individual.

“Most women have to try multiple contraceptive methods to find one that works well for them,” says Aaron Lazorwitz, MD, PhD, assistant professor of obstetrics, gynecology, and reproductive sciences at Yale School of Medicine. “No contraceptive method is perfect. And many women are frustrated with current options and the ‘trial-and-error’ aspect of the process.”

He and his research colleagues have been looking at individual genetic differences in hopes of explaining—and eventually predicting—how certain birth control methods will affect certain people. Their latest work, the largest pharmacogenomic study ever done on contraception, was published Feb. 27 in O&G Open.

“This research can be a potential tool to help women in the future feel that their experiences are not ‘in their heads’ as many are told, but could be due to real factors like genetics,” says Lazorwitz, a family planning expert and lead author of the study.

This latest research was built on earlier work by the team, which included efficacy-focused and weight-focused findings. Researchers analyzed 1.8 million genetic variants from 900 participants who used contraceptive implants, a birth control method in which a small rod that contains hormones is inserted under the skin of the upper arm.

“The contraceptive implant is the ideal method for this type of research because once the implant is in place, it releases a steady amount of hormone into the user’s body, and the individual doesn’t have to do anything to keep the implant working as it should,” says Lazorwitz.

Despite this steady release of hormone from the implant, individuals have widely variable drug levels of the hormone in their system, which the team believes plays a pivotal role in why some patients experience contraceptive failures even when using birth control perfectly. Although the team have not yet pinpointed specific parts of the genome that could clarify why the drug's effects vary so widely among users, they regard the findings as “fundamental groundwork” for a much larger discovery.

The human genome is immense. The number of participants and the expansive genetic variability collected from this study will be saved as initial data points and there are additional findings related to side effects coming soon. Also, Lazorwitz is using these results as preliminary evidence for his ongoing work, now expanding to oral contraceptive pill users. Researchers hope all this combined will tell a complete story of genetics and how it impacts contraception.

“If you look at other areas of medicine, it takes decades of research to finally identify the genetic variants that are clinically important, which then become clinical guidelines for actual practice,” says Lazorwitz. “This is an essential framework for advancing contraceptive care into the 21^st century and hopefully inspires other researchers to join this pursuit.”