A Cochrane review «»1 «Gallo MF, Lopez LM, Grimes DA, Schulz KF, Helmerho...»1 included 49 trials. The trials included 85 weight change comparisons for 52 distinct contraceptive pairs (or placebos). The four studies 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.
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison) and by limitations in study quality.