NuvaRing not affected by heavier body weight
The next patient in your exam room is in her mid-20s. While she is in generally good health, you note she weighs in at 210 pounds. What contraceptive methods do you offer her?
The contraceptive vaginal ring (NuvaRing, Organon, West Orange, NJ) may be an acceptable option. New research presented at the annual clinical meeting of the American College of Obstetricians and Gynecologists (ACOG) indicates that the ring’s effectiveness is not affected by heavier body weight.1 Results from the body weight analysis indicate that contraceptive efficacy was similar in all women, including heavier women weighing 189 to 272 pounds.1
"Based on the data we have thus far, NuvaRing seems a reasonable choice for women of any weight," says the paper’s presenter, Carolyn Westhoff, MD, MSc, professor of obstetrics and gynecology and public health at Columbia University in New York City.
Can weight be a factor?
Research has looked at the impact of weight on efficacy in other forms of contraception. In the case of the transdermal contraceptive (Evra, Ortho McNeil Pharmaceutical, Raritan, NJ), its labeling states that the method may be less effective in women at or above 198 pounds than in women with lower body weights. This precaution stems from an analysis of pooled data from three pivotal studies that indicates while contraceptive failure was low and uniformly distributed across the range of body weights in women below 198 pounds, in women at or above that weight, contraceptive failures may be increased.2
Two recent epidemiologic studies have found that being overweight may increase a woman’s risk of becoming pregnant while using oral contraceptives (OCs).3,4 Given the progressively higher prevalence of overweight and obesity in the United States in recent years, these results suggest that elevated body mass index (BMI) may be an increasingly important cause of unintended pregnancy among OC users, says Victoria Holt, PhD, MPH, a professor in the department of epidemiology at the University of Washington in Seattle who served as lead author for both studies.
The body weight data presented at the ACOG meeting came from a secondary analysis of the efficacy findings from the NuvaRing Phase III clinical database.
The distribution of pregnancies by subjects’ baseline body weight was analyzed by deciles for the intent-to-treat (ITT) and per-protocol (PP) populations. In total, 27 pregnancies occurred among 3,259 women in the ITT group (0.83%) and 12 pregnancies occurred in the 2,788 women in the PP group (0.43%). Pregnancies were evenly distributed over the baseline body weight deciles, demonstrating that NuvaRing was not associated with an increased risk of pregnancies in heavier women.1
Help women choose
As the authors of Contraceptive Technology advise, the best contraceptive method is the one that is medically appropriate and is used every time by someone happy with the method.5 As pointed out in a recent editorial, for women with medical problems, a useful formula for contraceptive choices weighs the risks of contraception vs. the risks of pregnancy in the absence of contraception.6 Using this approach, highly effective contraception often emerges as a priority for very heavy women.6
Effects of a birth control method on menses may be very important to a woman.5 Results from a controlled trial of women randomized to using an oral contraceptive or NuvaRing compared bleeding patterns for an 84-day period following immediate initiation of either method.7 Investigators found that the ring users experienced fewer days or episodes of bleeding-spotting and shorter intervals.7
"The women on NuvaRing had better bleeding patterns than those on the Pill; at the end of the study, the women on NuvaRing were much more likely to continue than women on the Pill," says Westhoff, who served as the paper’s lead author.
Westhoff uses what has been termed the "Quick Start" approach to initiating contraception, whereby women initiate their chosen birth control method at the provider’s office, regardless of where they are in their monthly cycle.8,9 Women had no trouble in beginning use of the vaginal ring in the office, Westhoff states.
"I think a lot of doctors worry that women are nervous about using NuvaRing," she observes. "We did not see that."
References
- Westhoff C. Higher body weight does not affect NuvaRing’s efficacy. Presented at the American College of Obstetricians and Gynecologists Annual Clinical Meeting. San Francisco; May 2005.
- Zieman M, Guillebaud J, Weisberg E, et al. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril 2002; 77(2 Suppl 2):S13-S18.
- Holt VL, Cushing-Haugen K, Daling JR. Body weight and risk of oral contraceptive failure. Obstet Gynecol 2002; 99:820-827.
- Holt VL, Scholes D, Wicklund KG, et al. Body mass index, weight, and oral contraceptive failure risk. Obstet Gynecol 2005; 105:46-52.
- Hatcher RA, Trussell J, Stewart F, et al. Contraceptive Technology: 18th revised edition. New York City: Ardent Media; 2004.
- Grimes DA, Shields WC. Family planning for obese women: Challenges and opportunities. Contraception 2005; 72:1-4.
- Westhoff C, Osborne LM, Schafer JE, et al. Bleeding patterns after immediate initiation of an oral compared with a vaginal hormonal contraceptive. Obstet Gynecol 2005; 106:89-96.
- Westhoff C, Kerns J, Morroni C, et al. Quick start: Novel oral contraceptive initiation method. Contraception 2002; 66:141-145.
- Lara-Torre E, Schroeder B. Adolescent compliance and side effects with Quick Start initiation of oral contraceptive pills. Contraception 2002; 66:81-85.
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