Unplanned Pregnancy With Weight Loss Drugs: Fact or Fiction?

Claudia* was a charming 27-year-old newlywed. She and her husband wanted to start a family — with one small catch. She had recently gained 30 pounds. During COVID, she and her husband spent 18 months camped out in her parents’ guest room in upstate New York and had eaten their emotions with abandon. They ate when they were happy and ate more when they were sad. They ate when they felt isolated and again when they felt anxious. It didn’t help that her mother was a Culinary Institute–trained amateur chef. They both worked from home and logged long hours on Zoom calls. Because there was no home gym, they replaced their usual fitness club workouts in the city with leisurely strolls around the local lake. When I met her, Claudia categorically refused to entertain the notion of pregnancy until she reached her pre-COVID weight.

At the time, this all seemed quite reasonable to me. We outlined a plan including semaglutide (Wegovy) until she reached her target weight and then a minimum of 2 months off Wegovy prior to conception. We also lined up sessions with a dietitian and trainer and renewed her birth control pill. There was one detail I failed to mention to her: Birth control pills are less effective while on incretin hormones like semaglutide. The reason for my omission is that the medical community at large wasn’t yet aware of this issue. 

About 12 weeks into treatment, Claudia had lost 20 of the 30 pounds. She had canceled several appointments with the trainer and dietitian due to work conflicts. She messaged me over the weekend in a panic. Her period was late, and her pregnancy test was positive.

She had three pressing questions for me:

Q: How had this happened while she had taken the birth control pills faithfully?

A: I answered that the scientific reasons for the decrease in efficacy of birth control pills while on semaglutide medications are threefold: 

• Weight loss can improve menstrual cycle irregularities and improve fertility. In fact, I have been using semaglutide-like medications to treat polycystic ovary syndrome for decades, well before these medications became mainstream.
• The delayed gastric emptying inherent to incretins leads to decreased absorption of birth control pills.
• Finally, while this did not apply to Claudia, no medicine is particularly efficacious if vomited up shortly after taking. Wegovy is known to cause nausea and vomiting in a sizable percentage of patients.

Q: Would she have a healthy pregnancy given the lingering effects of Wegovy?

A: The short answer is: most likely yes. A review of the package insert revealed something fascinating. It was not strictly contraindicated. It advised doctors to weigh the risks and benefits of the medication during pregnancy. Animal studies have shown that semaglutide increases the risk for fetal death, birth defects, and growth issues, but this is probably due to restrictive eating patterns rather than a direct effect of the medication. A recent study of health records of more than 50,000 women with diabetes who had been inadvertently taking these medications in early pregnancy showed no increase in birth defects when compared with women who took insulin.

Q: What would happen to her weight loss efforts?

A: To address her third concern, I tried to offset the risk for rebound weight gain by stopping Wegovy and giving her metformin in the second and third trimesters. Considered a safe medication in pregnancy, metformin is thought to support weight loss, but it proved to be ineffective against the rebound weight gain from stopping Wegovy. Claudia had not resumed regular exercise and quickly fell into the age-old eating-for-two trap. She gained nearly 50 pounds over the course of her pregnancy. 

After a short and unfulfilling attempt at nursing, Claudia restarted Wegovy, this time in conjunction with a Mediterranean meal plan and regular sessions at a fitness club. After losing the pregnancy weight, she has been able to successfully maintain her ideal body weight for the past year, and her baby is perfectly healthy and beautiful. 

*Patient’s name changed. 

A version of this article appeared on Medscape.com.

Claudia* was a charming 27-year-old newlywed. She and her husband wanted to start a family — with one small catch. She had recently gained 30 pounds. During COVID, she and her husband spent 18 months camped out in her parents’ guest room in upstate New York and had eaten their emotions with abandon. They ate when they were happy and ate more when they were sad. They ate when they felt isolated and again when they felt anxious. It didn’t help that her mother was a Culinary Institute–trained amateur chef. They both worked from home and logged long hours on Zoom calls. Because there was no home gym, they replaced their usual fitness club workouts in the city with leisurely strolls around the local lake. When I met her, Claudia categorically refused to entertain the notion of pregnancy until she reached her pre-COVID weight.

At the time, this all seemed quite reasonable to me. We outlined a plan including semaglutide (Wegovy) until she reached her target weight and then a minimum of 2 months off Wegovy prior to conception. We also lined up sessions with a dietitian and trainer and renewed her birth control pill. There was one detail I failed to mention to her: Birth control pills are less effective while on incretin hormones like semaglutide. The reason for my omission is that the medical community at large wasn’t yet aware of this issue. 

About 12 weeks into treatment, Claudia had lost 20 of the 30 pounds. She had canceled several appointments with the trainer and dietitian due to work conflicts. She messaged me over the weekend in a panic. Her period was late, and her pregnancy test was positive.

She had three pressing questions for me:

Q: How had this happened while she had taken the birth control pills faithfully?

A: I answered that the scientific reasons for the decrease in efficacy of birth control pills while on semaglutide medications are threefold: 

• Weight loss can improve menstrual cycle irregularities and improve fertility. In fact, I have been using semaglutide-like medications to treat polycystic ovary syndrome for decades, well before these medications became mainstream.
• The delayed gastric emptying inherent to incretins leads to decreased absorption of birth control pills.
• Finally, while this did not apply to Claudia, no medicine is particularly efficacious if vomited up shortly after taking. Wegovy is known to cause nausea and vomiting in a sizable percentage of patients.

Q: Would she have a healthy pregnancy given the lingering effects of Wegovy?

A: The short answer is: most likely yes. A review of the package insert revealed something fascinating. It was not strictly contraindicated. It advised doctors to weigh the risks and benefits of the medication during pregnancy. Animal studies have shown that semaglutide increases the risk for fetal death, birth defects, and growth issues, but this is probably due to restrictive eating patterns rather than a direct effect of the medication. A recent study of health records of more than 50,000 women with diabetes who had been inadvertently taking these medications in early pregnancy showed no increase in birth defects when compared with women who took insulin.

Q: What would happen to her weight loss efforts?

A: To address her third concern, I tried to offset the risk for rebound weight gain by stopping Wegovy and giving her metformin in the second and third trimesters. Considered a safe medication in pregnancy, metformin is thought to support weight loss, but it proved to be ineffective against the rebound weight gain from stopping Wegovy. Claudia had not resumed regular exercise and quickly fell into the age-old eating-for-two trap. She gained nearly 50 pounds over the course of her pregnancy. 

After a short and unfulfilling attempt at nursing, Claudia restarted Wegovy, this time in conjunction with a Mediterranean meal plan and regular sessions at a fitness club. After losing the pregnancy weight, she has been able to successfully maintain her ideal body weight for the past year, and her baby is perfectly healthy and beautiful. 

*Patient’s name changed. 

A version of this article appeared on Medscape.com.

Claudia* was a charming 27-year-old newlywed. She and her husband wanted to start a family — with one small catch. She had recently gained 30 pounds. During COVID, she and her husband spent 18 months camped out in her parents’ guest room in upstate New York and had eaten their emotions with abandon. They ate when they were happy and ate more when they were sad. They ate when they felt isolated and again when they felt anxious. It didn’t help that her mother was a Culinary Institute–trained amateur chef. They both worked from home and logged long hours on Zoom calls. Because there was no home gym, they replaced their usual fitness club workouts in the city with leisurely strolls around the local lake. When I met her, Claudia categorically refused to entertain the notion of pregnancy until she reached her pre-COVID weight.

At the time, this all seemed quite reasonable to me. We outlined a plan including semaglutide (Wegovy) until she reached her target weight and then a minimum of 2 months off Wegovy prior to conception. We also lined up sessions with a dietitian and trainer and renewed her birth control pill. There was one detail I failed to mention to her: Birth control pills are less effective while on incretin hormones like semaglutide. The reason for my omission is that the medical community at large wasn’t yet aware of this issue. 

About 12 weeks into treatment, Claudia had lost 20 of the 30 pounds. She had canceled several appointments with the trainer and dietitian due to work conflicts. She messaged me over the weekend in a panic. Her period was late, and her pregnancy test was positive.

She had three pressing questions for me:

Q: How had this happened while she had taken the birth control pills faithfully?

A: I answered that the scientific reasons for the decrease in efficacy of birth control pills while on semaglutide medications are threefold: 

• Weight loss can improve menstrual cycle irregularities and improve fertility. In fact, I have been using semaglutide-like medications to treat polycystic ovary syndrome for decades, well before these medications became mainstream.
• The delayed gastric emptying inherent to incretins leads to decreased absorption of birth control pills.
• Finally, while this did not apply to Claudia, no medicine is particularly efficacious if vomited up shortly after taking. Wegovy is known to cause nausea and vomiting in a sizable percentage of patients.

Q: Would she have a healthy pregnancy given the lingering effects of Wegovy?

A: The short answer is: most likely yes. A review of the package insert revealed something fascinating. It was not strictly contraindicated. It advised doctors to weigh the risks and benefits of the medication during pregnancy. Animal studies have shown that semaglutide increases the risk for fetal death, birth defects, and growth issues, but this is probably due to restrictive eating patterns rather than a direct effect of the medication. A recent study of health records of more than 50,000 women with diabetes who had been inadvertently taking these medications in early pregnancy showed no increase in birth defects when compared with women who took insulin.

Q: What would happen to her weight loss efforts?

A: To address her third concern, I tried to offset the risk for rebound weight gain by stopping Wegovy and giving her metformin in the second and third trimesters. Considered a safe medication in pregnancy, metformin is thought to support weight loss, but it proved to be ineffective against the rebound weight gain from stopping Wegovy. Claudia had not resumed regular exercise and quickly fell into the age-old eating-for-two trap. She gained nearly 50 pounds over the course of her pregnancy. 

After a short and unfulfilling attempt at nursing, Claudia restarted Wegovy, this time in conjunction with a Mediterranean meal plan and regular sessions at a fitness club. After losing the pregnancy weight, she has been able to successfully maintain her ideal body weight for the past year, and her baby is perfectly healthy and beautiful. 

*Patient’s name changed. 

A version of this article appeared on Medscape.com.