Contraceptive implants OK for overweight/obese women

• In CHOICE study, more than one-quarter of IUD or implant users were overweight and more than one-third were obese

• Cumulative failure rates were less than 1/100 women-years for both devices regardless of BMI

The etonogestrel subdermal contraceptive implant is just as effective in overweight and obese women as it is in women of normal weight and is as effective as an intrauterine device (IUD) (either the levonorgestrel intrauterine system or copper T380A), according to a recent study in Obstetrics and Gynecology.

Because trials conducted by manufacturers of these devices largely excluded women weighing more than 130% of ideal body weight and because some research has reported lower efficacy rates of hormonal contraceptive methods in overweight and obese women, researchers from St. Louis, MO, conducted the Contraceptive CHOICE Project, a large, prospective cohort study designed to encourage use of long-term reversible contraceptive methods in women in the St. Louis area. The Project provided women aged 14 to 45 with whatever reversible contraceptive method they wanted for free. The analysis included the first 8,445 enrollees in the CHOICE project, of which 1,168 chose the implant and 4,200 chose an IUD. The researchers recorded baseline height and weight and surveyed the participants periodically. If a woman suspected a pregnancy, they asked her to return to the clinic for a urine pregnancy test.

Of the women choosing the implant, 28% were overweight using National Health and Nutrition Examination Survey criteria (BMI 25-29.9) and 35% were obese (BMI 30 or greater). Similarly, of those choosing an IUD, 27% were overweight and 35% were obese. Cumulative failure rates over the 3-year period for both methods were less than 1 per 100 women-years, regardless of body mass index (BMI).

The researchers noted that compared with IUD users, implant users tended to be younger, black or Hispanic, single, and to have lower income and parity. Overweight and obese women were more likely to be older, black, married, less educated, uninsured, receiving public assistance, and of higher parity.

The researchers concluded that the study should provide reasonable assurance that these long-term contraceptive methods are highly effective regardless of BMI.

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