FPIN's Help Desk Answers
Hormonal Contraceptives in Women Who Are Overweight or Obese
Am Fam Physician. 2017 Jun 1;95(11):732.
Does excess body weight change the effectiveness of hormonal contraceptive methods?
Hormonal contraceptives (oral contraceptive pills, implants, patches, and rings) are highly effective in women of all weights. (Strength of Recommendation: A, based on a systematic review and cohort studies.) There is no consistently demonstrated increased risk of pregnancy in overweight women using any specific hormonal method of contraception.
A 2013 Cochrane review examined 13 trials of hormonal contraceptives with more than 49,000 sexually active women 18 to 49 years of age, comparing pregnancy rates across a range of body mass index (BMI) and weight strata.1 The primary outcome was pregnancy rates. In a secondary analysis of one of the randomized controlled trials included in the Cochrane review (n = 6,022) that analyzed two combined oral contraceptives (norethindrone/ethinyl estradiol and norgestimate/ethinyl estradiol), the only statistically significant finding was increased pregnancy risk in women with BMIs of 25 kg per m2 or greater who were using norethindrone (relative risk = 2.49; 95% confidence interval [CI], 1.01 to 6.13). Other secondary analyses evaluating different weight and BMI thresholds for norgestimate showed no difference in pregnancy risk. A post-hoc analysis of two randomized controlled trials and one observational study included in the review (N = 3,319) examined pregnancy rates in women using the norelgestromin/ethinyl estradiol transdermal patch by body weight deciles. Pregnancy was rare in any decile except the group with women weighing more than 90 kg (198.4 lb); however, statistical significance was not reported. The quality of evidence varied from very low to moderate because of the lack of adjustment for confounding factors. A prospective cohort study (n = 9,256) included in the Cochrane review examined the efficacy of the single-rod etonogestrel subdermal implant. The only pregnancy in this study occurred
1. Lopez LM, et al. Hormonal contraceptives for contraception in overweight or obese women. Cochrane Database Syst Rev. 2013;(4):CD008452.
2. McNicholas C, et al. Contraceptive failures in overweight and obese combined hormonal contraceptive users. Obstet Gynecol. 2013;121(3):585–592.
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