Small BMI changes with long-acting contraceptive may ‘alleviate’ weight gain concerns

Key takeaways:

• Adolescents who received an etonogestrel implant had a mean BMI change of approximately 1 U over 3 years.
• The observed weight change was slightly higher compared with weight-neutral or no contraceptives.

Adolescent and young adult women who initiated the etonogestrel contraceptive implant experienced small weight changes over 3 years similar to women who received depot medroxyprogesterone acetate, researchers reported.

In a retrospective study, researchers also found that BMI changes observed over a 3-year period with the two long-active contraceptive implants were higher compared with teens and young adults prescribed weight-neutral contraceptives or no contraceptives.

Weight gain has been a concern with progestin-only contraceptives with perceived effect on weight cited as the primary reason for discontinuation among adolescents and young adults, according to Hunter J. Wernick, DO, MS, pediatrician in the division of adolescent medicine at the Nationwide Children’s Hospital in Columbus, Ohio, but evidence on weight with the etonogestrel implant is more limited.

“A better understanding of the relationship between the etonogestrel implant and weight in the adolescent and young adult population would improve the evidence base for contraceptive counseling,” Wernick and colleagues wrote. “In addition, it would allow health professionals to potentially alleviate patient concerns about weight changes.”

Wernick and colleagues conducted a retrospective, longitudinal cohort study, published in Obstetrics & Gynecology, with 20,409 postmenarchal adolescent girls and young adult women. The etonogestrel implant and depot medroxyprogesterone acetate groups initiated their contraceptive choice from 2010 to 2017. Adolescents and young adults prescribed a weight-neutral contraceptive or no contraceptive during the same timeframe were included as controls.

Primary outcome was BMI over time measured as changes in BMI weight category at 12, 24 and 36 months.

Overall, 860 adolescents and young adults initiated etonogestrel (mean age, 16 years), 1,817 initiated depot medroxyprogesterone acetate (mean age, 15.9 years) and 17,732 were in the control group (mean age, 15.8 years).

Compared with controls, those in the etonogestrel group had a 0.5 U higher mean BMI at 9 months and a 10 U higher mean BMI at 36 months (P < .01 for both). Similarly, teens and young adults in the depot medroxyprogesterone acetate group had a 0.3 U higher mean BMI at 6 and a 1.3 U higher mean BMI at 36 months compared with the control group (P < .01 for both).

Increases in BMI weight categories of underweight, normal weight, overweight or obesity were rare in all three groups, regardless of weight changes.

According to the researchers, these findings align with previous studies that demonstrated similar BMI in women with an etonogestrel implant or depot medroxyprogesterone acetate and higher BMI for women with an etonogestrel implant vs. weight-neutral contraceptives or no hormonal contraceptives.

“For some patients, the 1-unit difference in BMI noted at 36 months in our study may

not be clinically concerning, particularly because we found that most patients remained in their starting BMI weight category over time,” the researchers wrote. “However, other

patients may be quite sensitive to weight changes, underscoring the need for patient-centered counseling and informing expectations.”