Does Obesity Influence Body Mass Index Changes in Nulliparous Adolescent Users of Long-Acting Reversible Contraceptives?

Abstract

To compare body mass index (BMI) changes in adolescents using long-acting reversible contraceptives (LARCs), specifically, the etonogestrel subdermal implant (ENG-implant), levonorgestrel intrauterine device (LNG-IUD), and copper IUD (Cu-IUD), by initial BMI category from the time of LARC insertion to within 6-18 months after insertion. This was a single-center retrospective cohort study. We reviewed electronic health records from our large health system to identify and follow a cohort of 196 adolescents aged 14-19 years with LARCs inserted from 2010 to 2016. We excluded adolescents with conditions or medications affecting weight, including childbirth. BMI change from LARC insertion to first BMI documented after 6-18 months RESULTS: Mean age was 17.2 ± 0.2 years; 59% of the cohort was Hispanic and 29% Black. Mean BMI was 26.4 ± 7.1 kg/m2. Of the total cohort of adolescents, 51% were underweight/normal, 24% overweight, and 25% obese. Mean time to first BMI documented after LARC insertion was 10.1 ± 3.2 months. Mean BMI change for the total cohort was +0.73 ± 1.8 kg/m2, indicating weight gain. Mean BMI change for the ENG-implant+LNG-IUD users (n=127) was larger than for Cu-IUD users (n=69) (+0.92 ± 1.9 kg/m2 vs +0.37 ± 1.6 kg/m2, respectively, P < .05). Two-way analysis of variance showed that both initial BMI category (P=.001) and type of LARC (P=.011) had an independent significant main effect on BMI change. A significant interaction effect (P=.017) showed that obese adolescents had a larger increase in BMI when they were using a progestin-releasing LARC, either ENG-implant or LNG-IUD, as compared to a Cu-IUD (P < .05). Adolescents using progestin-releasing LARCs had a larger increase in BMI within 6-18 months after device insertion than those using Cu-IUDs. The disproportionate increase in BMI with progestin-releasing LARCs was primarily contributed by obese users.