Progestin-only contraceptives: effects on weight.

Progestin-only contraceptives (POCs) are appropriate for many women who cannot or should not take estrogen. Many POCs are long-acting, cost-effective methods of preventing pregnancy. However, concern about weight gain can deter the initiation of contraceptives and cause early discontinuation among users. The primary objective was to evaluate the association between progestin-only contraceptive use and changes in body weight. We searched MEDLINE, CENTRAL, POPLINE, EMBASE, LILACS, ClinicalTrials.gov, and ICTRP, and contacted investigators to identify other trials. All comparative studies were eligible that examined a POC versus another method or no contraceptive. The primary outcome was mean change in body weight or body composition. Two authors extracted the data. We computed the mean difference with 95% confidence interval (CI) for continuous variables and odds ratio with 95% CI for dichotomous variables. We did not conduct meta-analysis due to the various contraceptive methods and weight change measures. Fifteen studies examined progestin-only pills (N=1), Norplant (N=4), and depot medroxyprogesterone acetate (DMPA) (N=10). Comparison groups were similar for weight change in 11 studies. Four studies showed differences in weight or body composition change for POCs compared to no hormonal method. Adolescents using DMPA had a greater increase in body fat (%) versus a group using no hormonal method (mean difference 11.00; 95% CI 2.64 to 19.36). The DMPA group also had a greater decrease in lean body mass (%) (mean difference -4.00; 95% CI -6.93 to -1.07). In another study, weight gain (kg) was greater for the DMPA group than an IUD group (mean difference 2.28, 2.71, 3.17, respectively). The differences were notable within the normal weight and overweight subgroups. One study showed the Norplant (six-capsule) group had greater weight gain (kg) than a non-hormonal IUD group (mean difference 0.47 (95% CI 0.29 to 0.65) and a group using non-hormonal or no method (mean difference 0.74; 95% CI 0.52 to 0.96). Another study also showed a Norplant group also had greater weight gain (kg) than an IUD group (mean difference 1.10; 95% CI 0.36 to 1.84). We found little evidence of weight gain when using POCs. Mean gain was less than 2 kg for most studies up to 12 months, and usually similar for the comparison group using another contraceptive. Appropriate counseling about typical weight gain may help reduce discontinuation of contraceptives due to perceptions of weight gain.