By Melinda Young
Clinicians providing contraceptive counseling should be aware of recent research showing that young people can experience weight gain when using hormonal implants, when compared with young people using some other types of contraceptives.1
Researchers found that adolescents and young adults who start using the etonogestrel implant experience a mean body mass index (BMI) change of about one unit over a three-year period. But the change did not cause someone who was at normal weight to become overweight or someone who was overweight to become obese, meaning it was not a big concern medically.1
“The reason we did this study was because there’s been a lot of concerns around [weight] and combined contraceptives,” says Andrea Bonny, MD, section chief of adolescent medicine at Nationwide Children’s Hospital and professor of clinical pediatrics at The Ohio State University in Columbus. “We had patients who said they gained weight on it, but we didn’t have good data on it, and we wanted to look at data around weight and use of the implant,” she adds.
The study looked at more than 20,000 eligible patients, of whom 860 initiated use of an etonogestrel implant, 1,817 initiated depot medroxyprogesterone acetate (DMPA), and 17,732 were in the control group. Participants were patients in an urban, free-standing children’s hospital and were post-menarchal young people, ages 13 to 21 years, assigned female at birth.1
Investigators were surprised by the BMI data on implant use in youths. “The implant looked exactly like the [Depo-Provera] group, which was a surprise to us and not what we hypothesized,” Bonny says. “The two paralleled each other over a three-year time period.” Weight gain is a side effect listed for DMPA. “I have many patients who have been on Depo for years and are very happy,” Bonny says.
Patients using DMPA and the etonogestrel implant had higher mean BMI numbers at nine months and 36 months after initiation when compared with the control group. But increases in BMI weight categories were rare in all groups.1 “We had a large population, and we excluded anything we could think of that could potentially cause weight gain,” Bonny says. “These were relatively healthy populations we looked at, and Depo and the implant were similar over the time period; both had significantly higher BMI than the control group.”
The study did not look at weight perceptions of participants and whether this affected their decision to stay on their contraceptive or change it. “We did not collect self-reports. Prior studies have done that, and they noticed that patients who quit because of weight seemed to gain more weight compared with those who continued the contraceptive,” Bonny says. “There was a lot of attrition, but we don’t know if people who didn’t come back were happy and didn’t come back, so we may be overestimating the BMI. They may have gone to another institution.”
Many contraceptive methods have a risk of weight gain, and clinicians need to be concerned about this since it can be an issue for patients, she notes. “Follow their weight trajectory,” Bonny suggests. “I do a six-month check with all Depo patients to check how they’re weight’s going and if they have any concerns around it.”
Patients who are satisfied with their weight on the contraceptive can be monitored. Those who experience a weight increase that troubles them can stop the contraceptive, if they want.
“As I saw this data, I’m going to be more mindful when I counsel patients about the implant, saying it might not be a weight-neutral method,” she says. “I say, ‘Let’s follow you, and if there’s a problem, we can discuss it and see if you’d like to switch to something else.’” If patients prefer a weight-neutral method, they can be offered hormonal contraceptive pills that are weight neutral for most people, she adds.
“Some people are on Depo for years, and they do not gain weight and are happy with it,” Bonny says. “We need to counsel our patients appropriately.”
But clinicians also should not discourage patients from using the implant because it is a great method that is highly effective and very safe. Weight gain is a manageable side effect. “It’s still a very safe method, and we should encourage patients to use it. But we need to manage their expectations,” Bonny explains. “What I would say is that, over three years, there is, for some people, a risk of an increase in weight, but it’s rare for someone who is normal weight to become overweight.”
Melinda Young has been a healthcare and medical writer for 30 years. She currently writes about contraceptive technology.
Reference
- Wernick HJ, Abedl-Rasoul M, Berlan ED, Bonny AE. Body mass index changes among adolescents and young adults using etonogestrel contraceptive implant. Obstet Gynecol. 2024;144:553-561.
Clinicians providing contraceptive counseling should be aware of recent research showing that young people can experience weight gain when using hormonal implants, when compared with young people using some other types of contraceptives.
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