Combination contraceptives: effects on weight.

Abstract

Weight gain is often attributed as a side effect of combination hormonal contraceptive, and many women and clinicians believe that an association exists. Concern about weight gain can limit the use of this highly effective method of contraception by deterring the initiation of its use and causing early discontinuation among users. Nevertheless, a causal relationship between combination contraceptives and weight gain has not been established. The aim of the review was to evaluate the association between combination contraceptive use and changes in weight. We searched the computerized databases MEDLINE, Popline, CENTRAL, EMBASE, and LILACS for studies of combination contraceptives. We also wrote to known investigators and manufacturers to request information about other published or unpublished trials not discovered in our search. All English-language, randomized controlled trials at least three treatment cycles in duration that compared a combination contraceptive to a placebo or with a combination contraceptive that differed in drug, dosage, regimen, and/or study length were eligible. All titles and abstracts located in the literature searches were assessed. Data were entered and analyzed with RevMan 4.1, and a second reviewer verified the data entered. Depending on the data available, the weighted mean difference using a fixed effects model with 95% confidence intervals was calculated for the mean change in weight between baseline and post-treatment measurements or the Peto odds ratio with 95% confidence intervals was calculated using the proportion of women who gained or lost more than a specified amount of weight. The three placebo-controlled, randomized trials did not find evidence supporting a causal association between combination oral contraceptives or a combination skin patch and weight gain. Most comparisons of different combination contraceptives showed no substantial difference in weight. In addition, discontinuation of combination contraceptives because of weight gain did not differ between groups where this was studied. Available evidence is insufficient to determine the effect of combination contraceptives on weight, but no large effect is evident.