Is NuvaRing's effectiveness mitigated by weight?
February 22, 2010 6:38 AM   Subscribe

Is NuvaRing's effectiveness mitigated by weight?

I know, you are not my doctor and a real doctor is researching this, but if anyone with some education in the field could shed some light, I would appreciate it. All I can find is discussion about how it may cause weight gain. I want to know if a person is overweight, would it result in ineffective birth control and potentially pregnancy?
posted by anonymous to Health & Fitness (2 answers total) 1 user marked this as a favorite
C Westhoff - Obstetrics & Gynecology, 2005

Higher Body Weight Does Not Affect NuvaRing’s Efficacy
Carolyn Westhoff, MD
Columbia University, New York, NY

OBJECTIVES: NuvaRing, the monthly contraceptive method, has been shown to be effective in clinical trials and daily life. Because a higher incidence of pregnancies has been reported in women with greater body weight (198 pounds and more) with other hormonal contraceptive methods, an analysis was performed to see whether there was any relationship between subjects’ body weight and contraceptive efficacy during the NuvaRing clinical trial program.

METHODS: A secondary analysis of the NuvaRing phase III clinical database (efficacy trials) was performed. The distribution of pregnancies by subjects’ baseline body weight was analyzed by deciles for both the intent-to-treat (ITT) and per-protocol (PP) populations.
RESULTS: Twenty-seven pregnancies occurred in the ITT group (n  3,259; weight range 88–272 pounds) and 12 in the PP group (n  2,788; weight range 88–253 pounds), giving a pregnancy rate of 0.83% and 0.43%, respectively. The ITT pregnancies were evenly distributed over the baseline body weight deciles (range 0–4 pregnancies). Four ITT pregnancies occurred in the highest decile (167 pounds and over n  343; pregnancy rate of 1.2%). Exclusion of protocol violations gave 3 PP pregnancies in the highest decile (n295; pregnancy rate of 1%). The 27 pregnancies occurred in women with baseline weight of 106–188 pounds. No pregnancies occurred in the 74 heavier women (189–272 pounds), including the 41 women who weighed 198 pounds and more; these are the women for whom there is currently the most concern over possible weight related contraceptive failure.

CONCLUSION: NuvaRing is not associated with an increased failure rate among heavier women.

posted by Comrade_robot at 6:51 AM on February 22, 2010

In fact, NuvaRing has a better track record with this than more-systemic forms of hormonal birth control. All forms of the pill, for example, have to enter your bloodstream by way of your gut before the hormones will get to your reproductive organs. So, if you are a larger person, you will need a larger dose of oral contraceptive -- compounded by the facts that steroid hormones are fat-soluble and therefore tend to go there, and that fat itself produces hormones.

Since NuvaRing delivers its hormones more locally, this effect is mitigated, so heavier women do not have an increased failure rate (as per the above article).

If you're worried about failure rates of different contraceptives, you might also be interested in looking at the modern IUDs. I can't use other hormonal contraceptives because of bad side effects, but I'm in my 4th year with the Mirena, it's worked very well, I haven't had the fits of acne, crippling depression, and weight gain that I experienced with Every. Single. Other. Method., and it has a lower failure rate than any other hormonal method and should work regardless of whether or not a woman is overweight.
posted by kataclysm at 10:11 AM on February 22, 2010

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