Contraceptive vaginal ring effectiveness is maintained during 6 weeks of use: a prospective study of normal BMI and obese women

Abstract

Background A single study shows that contraceptive vaginal ring (CVR) use for up to 35 days in women with a normal BMI maintains serum hormone levels sufficient to suppress ovulation. This study is intended to confirm those results and to evaluate prolonged CVR use up to 42 days in both normal BMI and obese women. Study Design Twenty women with a normal BMI and 20 obese women enrolled in a prospective open label clinical study of ethinyl estradiol (EE) and etonogestrel (ENG) pharmacokinetics during six weeks of use of a single CVR. Participants underwent twice weekly evaluations to determine serum hormone concentrations, ovarian follicle development, endometrial thickness and bleeding patterns. Results Thirty-seven women completed follow-up including eighteen women with a normal BMI and nineteen obese women. EE and ENG concentrations remained in therapeutic range for all women. Follicular development and endometrial proliferation were minimal. By the sixth week, 30% of participants reported spotting or bleeding. Conclusions A single CVR used for six weeks demonstrates therapeutic serum levels of EE and ENG among women with normal and obese BMI. Women who forget to remove the CVR at day 21 may well have continued contraceptive protection during the next three weeks.

Hormonal Contraception: Systemic Estrogen and Progestin Preparations

“…However, a prospective study involving 20 normal weight and 20 obese women found similar rates of suppression of ovarian follicle development among the 2 groups 40. This same study noted ovarian suppression with continuous use of a single vaginal ring maintained in place for up to 6 weeks 41…”

“…The hormones are absorbed directly by the vaginal mucosa and avoid first-pass metabolism, similar to the transdermal patch. This vaginal ring is marketed for use for a 21 days followed by 7-day hormone-free days, though it likely maintains sufficient serum hormone levels to suppress ovulation for 35 days and as many as 42 days when cycled with an extended-use pattern 41,125. Studies comparing serum EE concentrations among users of COCs, the Xulane transdermal patch, and the vaginal ring found significantly lower levels among vaginal ring users 122…”

“…This vaginal ring is marketed for use for a 21 days followed by 7-day hormone-free days, though it likely maintains sufficient serum hormone levels to suppress ovulation for 35 days and as many as 42 days when cycled with an extended-use pattern. 41,125 Studies comparing serum EE concentrations among users of COCs, the Xulane transdermal patch, and the vaginal ring found significantly lower levels among vaginal ring users. 122 A newer vaginal ring called Annovera was approved by the FDA in 2018 and is now available in the United States.…”

“…40 This same study noted ovarian suppression with continuous use of a single vaginal ring maintained in place for up to 6 weeks. 41…”

FSRH Guideline (April 2019) Overweight, Obesity and Contraception

“…The researchers concluded that the findings predict that ring effectiveness will be similar in women with a BMI up to 39.9 kg/m 2 157. In another pharmacokinetic analysis comparing 20 women with a normal BMI and 20 women with obesity, a single ring used for 6 weeks demonstrated therapeutic serum levels of EE and ENG among women with normal and obese BMI 158. Although reassuring, these studies were conducted over only one cycle in small groups of women.…”