Vaginal Ring Provides Effective Cycle Control, Reduced Bleeding With Extended Regimen, Study Finds

October 29, 2009 — Summary of "Extended Regimens of the Vaginal Contraceptive Ring: Cycle Control," Aparecida Falbo Guazzelli et al., Contraception, November 2009.

FDA approved the vaginal ring as a new form of contraception in 2002. The ring operates by releasing daily doses of etonogestrel and ethinyl estradiol and was intended to be used for 21 consecutive days followed by a seven-day pause. Previous studies have established that the ring is simple to use and effective as a monthly contraceptive, with good cycle control and stable hormone levels.

Cycle control influences a contraceptive's acceptance, compliance and convenience. Previous studies have shown that "cycle control with vaginal ring was superior to that of a hormonal oral contraceptive," with users experiencing lower incidence rates of irregular bleeding and spotting. "Oral contraceptives used for extended periods of time have been extensively studied because of their potential benefits, such as reduction in bleeding and premenstrual symptoms," but similar research has not been conducted for extended use the vaginal ring, according to the study's authors.

The study sought to compare bleeding during extended use of the vaginal ring with that of oral contraceptives. The researchers also sought to track the rate of discontinuation for both forms of contraception and evaluate why women discontinued use.

Methods: The study's participants included 150 women who sought contraception at the Gynecology Clinic of Western Paulista University in Sao Paulo, Brazil. Women were invited to join the program between April 2004 and March 2005 and were divided evenly between groups using vaginal rings and oral contraception for one year. The women were evaluated at enrollment and every month for one year.

Women using the vaginal ring were instructed to leave the ring in place for 21 days and then replace it with a new one. The cycle repeated four times for a total of 84 days. After the fourth ring, they were to wait seven days before introducing a new one. Women using oral contraceptives were instructed to take one pill daily for 84 days and then pause for seven days before resuming pills. Thus, over one year, women in each group used their contraception in four cycles of 91 days each. The women also completed diaries detailing information about missed pills, the occurrence and intensity of spotting and bleeding, and any other symptoms they experienced during the year-long evaluation. The researchers recorded the data in the diaries each month.

Results:No pregnancies occured during the study. The rate of discontinuation after one year was 17.3% in the vaginal ring group and 18.4% in the oral contraceptive group. The most frequent reasons for discontinuation were irregular bleeding in the ring group (4%) and nausea, vomiting or stomach pain in the oral contraceptive group (6.6%).

The average total number of scheduled bleeding days was 15.4 in ring users and 13.9 in oral contraceptive users. Over the one-year period, there was a significant decrease in the number of bleeding days for both groups, with the number of days significantly lower for oral contraceptive users compared with ring users.

The average number of scheduled bleeding/spotting days was 16.3 for ring users and 14.2 for oral contraceptive users. There was a significant reduction in the number of scheduled bleeding/spotting days for both groups, but the reduction was significantly higher among the oral contraceptive group.

There was also a significant reduction in the number of unscheduled bleeding days for both methods, with the reduction significantly higher among ring users. The mean number of unscheduled bleeding/spotting days was 21.7 days for ring users and 22.9 for oral contraceptive users.

Discussion: Good cycle control "is very important in any form of hormonal contraception since it is a strong predictor of patient compliance," the researchers wrote. They found that the "total mean number of bleeding days per year for each of these methods was the same, approximately 32 days," which represents 2.7 days per cycle over one year. That figure is less than the number of bleeding days experienced without hormone use. It is also less than the number of bleeding days experienced with the use of 28-day pills.

The study showed similar discontinuation rates for both methods. Though irregular bleeding was the main reason for ring discontinuation, the absolute value (4%) was much lower than previously reported for conventional ring regimens (23%) or extended regimens (35.8%). For oral contraceptives, gastric intolerance was the main reason for oral contraceptive discontinuation, affecting 6.6% of users, which is much lower than previously reported elsewhere (43%).

The authors concluded that using a vaginal ring containing etonogestrel and ethinyl estradiol for an extended regimen is a "contraceptive method that offers good cycle control" and "can be an option for women that have gastric intolerance or other side effects when using oral hormonal contraceptives."