SAN FRANCISCO — The NuvaRing contraceptive appears to be as effective in women who weigh more than 89.9 kg (198 lbs.) as in women who weigh less, Carolyn Westhoff, M.D., reported in a poster presentation at the annual meeting of the American College of Obstetricians and Gynecologists.
Previous reports have shown higher incidence of pregnancies with other hormonal contraceptive methods among patients weighing more than 89.9 kg. No causal relationship between body weight and pregnancy risk has been shown, said Dr. Westhoff of Columbia University in New York.
Dr. Westhoff conducted a retrospective analysis of four phase III studies sponsored by Organon Inc., NuvaRing's manufacturer. Together, these trials included 3,259 in the intent-to-treat (ITT) population. Of those, 2,788 women were treated per protocol (PP). There were 27 pregnancies in the ITT group (0.83%) and 12 in the PP group (0.43%).
There were no significant differences in the number of pregnancies in each decile of body weight. There were 41 women in the studies who weighed at least 89.9 kg. None of these women became pregnant.