Everything You Need to Know About Weight-Loss Drugs and Birth Control

It’s also important to know that vomiting and diarrhea are potential side effects for all GLP-1 drugs, and this can compromise the effectiveness of oral birth control. If you vomit within three hours of taking your birth-control pill, or experience diarrhea for more than 24 hours, experts recommend using condoms as backup and consulting with your doctor on how to proceed going forward.

Then there’s one more factor to weigh in when you’re a woman of childbearing age on weight-loss medication: People who are obese and lose a significant amount of weight frequently begin to experience more regular periods, more balanced hormones, and improved ovulation, especially if they have polycystic ovary syndrome (PCOS). These changes have the potential to lead to surprise pregnancies. “Many women who are overweight or obese have tried unsuccessfully to get pregnant in the past, but once they start to lose weight, they find themselves pregnant,” says Dr. Jennifer Brown, MD, a board-certified obesity medicine doctor at MyObesityTeam.

In some cases, there’s also a delay in women taking GLP-1s medications, figuring out that they’re pregnant—when you’re used to irregular periods, it can be harder to notice missing one. That’s concerning because the risks that weight-loss medications pose to pregnant women and their babies are still unknown. Some animal studies have linked them to increased risk of miscarriage and birth defects (though population-based studies have not confirmed this), and like many drugs, they have not been clinically tested in pregnant women.

“Most of these drugs should not be taken during pregnancy due to potential risks,” advises Dr. Christine Ren-Fielding, Professor of Surgery at NYU School of Medicine, Director of the NYU Langone Weight Management Program and Chief of the Division of Bariatric Surgery. “For this reason, if you are on a weight-loss medication, you should also be on a reliable form of birth control. If you are planning to become pregnant, you must stop taking these medications beforehand.”

As a general rule, women should discontinue weight-loss medications at least two months prior to a planned pregnancy, unless advised otherwise by a doctor (in some cases, the benefits of using one of these medications during pregnancy—such as to treat diabetes—may outweigh the potential risks).

To better understand the risks weight-loss medications pose during pregnancy, manufacturers of GLP-1 drugs have created registries for collecting data from people who get pregnant while using them. For the time being, anyone using weight-loss medication who wants to get pregnant should work with an obesity specialist in addition to an ob-gyn before, during, and after pregnancy to ensure that their pursuit of a healthy weight doesn’t interfere with their chances of having a healthy pregnancy.