Abstract

Background: This meta-analysis evaluated the effects of hormonal contraceptives on body weight using randomized controlled trials (RCTs) that included non-hormonal control groups such as copper intrauterine devices (IUDs), condoms, placebo, or no contraception. Methods: We systematically searched electronic databases for RCTs involving premenopausal women that reported at least one primary outcome (body weight or body mass index [BMI]). Secondary outcomes included waist circumference, body composition, blood pressure, and glucose, insulin, and lipid profiles. Results: Seven RCTs involving 9,331 premenopausal women were included. Interventions included oral contraceptives, depot injections, subdermal implants, and hormonal IUDs, with follow-up durations ranging from 6 to 18 months. Hormonal contraceptives were associated with a small but statistically significant increase in weight (weighted mean difference [WMD], 0.07; 95% confidence interval [CI], 0.02 to 0.12). Greater weight gain was observed with non-oral methods (WMD, 0.08; 95% CI, 0.03 to 0.12) and at time points >12 months (WMD, 0.08 kg; 95% CI, 0.02 to 0.14). The BMI also increased slightly (WMD, 0.07; 95% CI, 0.01 to 0.14). In observations >12 months, a significant increase in BMI was noted (WMD, 0.08; 95% CI, 0.01 to 0.16), although no significant difference was found by route of administration. No significant changes were observed in waist circumference, body fat, blood pressure, glucose or insulin levels. A small reduction in total cholesterol was observed (WMD, –0.36; 95% CI, –0.70 to –0.02), while other lipid markers remained stable. Conclusion: Hormonal contraceptives may cause slight increases in body weight and BMI, particularly with long-term or non-oral use. These findings should be interpreted with caution due to limited data quality.