Ashley M. Nault, from the Washington University School of Medicine in St. Louis, and colleagues analyzed self-reported weight change data from 4,133 new contraceptive method users at three, six, and 12 months after enrollment. To assess the validity of self-reported weight gain, data were examined for a subgroup of participants with objective weight measurements at baseline and 12 months.The researchers found that weight gain was perceived by 34 percent of participants. Implant users and depot medroxyprogesterone acetate users were more likely to report perceived weight gain than copper intrauterine device users (relative risk, 1.29 and 1.37, respectively). There was a mean actual weight gain of 10.3 pounds in women who perceived weight gain. The sensitivity of perceived weight gain was 74.6 percent and the specificity was 84.4 percent.