• Mean ovarian follicular development by week [ Time Frame: Transvaginal ultrasound measurements of ovarian follicular development will be completed twice weekly during four weeks of continuous ring use ] [ Designated as safety issue: No ]
• Mean endometrial proliferation by week [ Time Frame: Transvaginal ultrasound measurements of endometrial proliferation will be completed twice weekly during four weeks of continuous ring use ] [ Designated as safety issue: No ]
• Compare ovarian suppression in oral contraceptive users and Nuvaring users [ Time Frame: Transvaginal ultrasound measurements and serum hormone measurements taken twice a week for 6 weeks on Nuvaring and Twice a week for 4 weeks on COCs. ] [ Designated as safety issue: No ]

• Mean ovarian follicular development by week [ Time Frame: Transvaginal ultrasound measurements of ovarian follicular development will be completed twice weekly during four weeks of continuous ring use ] [ Designated as safety issue: No ]
• Mean endometrial proliferation by week [ Time Frame: Transvaginal ultrasound measurements of endometrial proliferation will be completed twice weekly during four weeks of continuous ring use ] [ Designated as safety issue: No ]

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 will focus on evaluating mean serum concentrations of hormones released in obese and normal weight women using the NuvaRing® . This study is 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 will recruit 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 will compare mean serum concentrations of ethinyl estradiol (E2) and etonogestrel (ENG) along with additional markers for ovarian suppression. These markers include 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 translate to understanding contraceptive-mediated suppression of ovarian function in these two groups. We will also have subjects log patterns of ring use and bleeding patterns during the study period.

• Experimental: Obese subjects (BMI 30-39.9)
• Active Comparator: Normal weight subjects (BMI 19-24.9)

• 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.
• Sivin I, Lähteenmäki 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.
• 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.
• 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.
• 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.

Inclusion Criteria:

• 18-35 yo
• Meet BMI requirements
• Weight stable
• English speaking
• Desire contraception
• History of regular menses with normal uterus and ovaries
• Medically eligible for combined hormonal contraception
• Tolerates phlebotomy/TVS

Exclusion Criteria:

• Exclusion:
• Heavy smokers
• Users of medications that alter hormone levels