Hormonal intrauterine devices (IUDs) and contraceptive implants remain highly effective even one year beyond their approved duration of use, according to a new study.

Now the researchers are evaluating whether such long-acting forms of birth control are effective for up to three years past the length of use under which they were approved by the Food and Drug Administration (FDA). Contraceptive implants - matchstick-sized rods inserted into the arm - are approved for three years while hormonal IUDs are approved for five years.

Medical companies have to be conservative in modern litigious society but earlier studies conducted by the World Health Organization and European researchers also found that IUDs and implants may be effective for longer periods of time. So in countries where the cost is prohibitive this has value. No doctor, and certainly not the FDA, is going to recommend longer use and companies would likely also lobby against it to prevent potential lawsuits if someone does get pregnant.

The researchers evaluated the hormonal IUD Mirena and contraceptive implants Implanon and Nexplanon and included 237 women who used implants and 263 women who used hormonal IUDs. Study participants were 18 to 45 years old, and their contraceptives had to be within six months of expiring when they enrolled. The women were informed of a possible risk of pregnancy if the devices were used beyond the time periods approved by the FDA.

The researchers documented no pregnancies in the implant group and one pregnancy in the IUD group. This failure rate is similar to that of IUDs used within the recommended five-year window of time. The researchers will continue to follow the women and others who enroll in the study. The final results will determine if contractive IUDs and implants are effective for up to three years beyond FDA-approved duration of use.

Citation: McNicholas C, Maddipati R, Zhao Q, Swor E, Peipert JF. Use of the estronogestrel implant and levonorgestrel intrauterine device beyond the U.S. Food and Drug Administration-approved duration. Obstetrics&Gynecology, Feb. 5 2015.  This project was supported by the Society of Family Planning; the Washington University Institute of Clinical and Translational Sciences National Center for Research Resources, grant UL1; the National Center for Advancing Translational Sciences, grant RR024992; the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NIH), award T32HD055172; and an anonymous foundation.