Comparison of Serum Contraceptive Hormone Levels Between Normal Weight and Obese Users of the NuvaRing®

Summary

There are over 60 million women of reproductive age in the U.S. and a majority of these women qualify as overweight or obese. Evidence suggests that there is an association between increased body weight and decreased contraceptive efficacy. Studies with the combined hormonal contraceptive patch (Evra®) and the subdermal contraceptive implant (Norplant®) demonstrate higher failure rates in heavier versus lighter women. Weight related differences in the effectiveness of NuvaRing® need further study. A single secondary analysis of pooled data from Phase III clinical trials of NuvaRing® noted no difference in pregnancy rates among women in the highest weight decile (\>166#) versus the rest of the study population using the ring. (Westhoff, 2005) The finding of no difference, however, was influenced by too few obese subjects in the analysis which contributed to wide confidence limits. Additional studies are needed to explore how well the contraceptive ring functions to maintain effective serum steroid concentrations to suppress ovarian activity in obese women. This investigation focused on evaluating mean serum concentrations of hormones released in obese and normal weight women using the NuvaRing® . This study was a prospective clinical trial. Normal weight women are defined as women with a BMI 19-24.9 and obese women are those with a BMI 30-39.9. We recruited forty adult women interested in initiating the combined hormonal contraceptive ring to two months of use to complete analysis of at least 34 subjects (17 normal weight, 17 obese). We compared mean serum concentrations of ethinyl estradiol (E2) and etonogestrel (ENG) along with additional markers for ovarian suppression. These markers included sonographic evidence of follicular development and ovulation as well as circulating E2 levels which strongly correlate with follicular development and endometrial proliferation during the second month of NuvaRing® use. Assessment of these parameters will translated to understanding contraceptive-mediated suppression of ovarian function in these two groups. Subjects also logged patterns of ring use and bleeding patterns during the study period.

Timeline

Start

2008-06

Primary completion

2008-12

Completion

2008-12

Publications

• Background Gu S, Sivin I, Du M, Zhang L, Ying L, Meng F, Wu S, Wang P, Gao Y, He X, et al. Effectiveness of Norplant implants through seven years: a large-scale study in China. Contraception. 1995 Aug;52(2):99-103. doi: 10.1016/s0010-7824(95)00141-7.
• Background Sivin I, Lahteenmaki P, Mishell DR Jr, Alvarez F, Diaz S, Ranta S, Grozinger C, Lacarra M, Brache V, Pavez M, Nash H, Stern J. First week drug concentrations in women with levonorgestrel rod or Norplant capsule implants. Contraception. 1997 Nov;56(5):317-21. doi: 10.1016/s0010-7824(97)00153-4.
• Background Sivin I, Wan L, Ranta S, Alvarez F, Brache V, Mishell DR Jr, Darney P, Biswas A, Diaz S, Kiriwat O, Anant MP, Klaisle C, Pavez M, Schechter J. Levonorgestrel concentrations during 7 years of continuous use of Jadelle contraceptive implants. Contraception. 2001 Jul;64(1):43-9. doi: 10.1016/s0010-7824(01)00226-8.
• Background Smallwood GH, Meador ML, Lenihan JP, Shangold GA, Fisher AC, Creasy GW; ORTHO EVRA/EVRA 002 Study Group. Efficacy and safety of a transdermal contraceptive system. Obstet Gynecol. 2001 Nov;98(5 Pt 1):799-805. doi: 10.1016/s0029-7844(01)01534-4.
• Background Westhoff, C. Higher body weight does not affect NuvaRing's efficacy. Obstet Gynecol 2005; 104: 56S.
• Background Zieman M, Guillebaud J, Weisberg E, Shangold GA, Fisher AC, Creasy GW. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril. 2002 Feb;77(2 Suppl 2):S13-8. doi: 10.1016/s0015-0282(01)03275-7.

Drugs

Indications

No indication recorded.