Extended use of the implant and LNG-IUS

New evidence shows these long-acting methods keep working for at least a year after their expiration.

by Colleen McNichols, DO, MSCI

published 07/31/15

Your client says: “I love my implant but it’s expiring. I don’t have insurance to cover a new one, so I guess I’ll just use condoms.”

There’s good news! Your client can keep using the method she loves. Although the implant is currently approved by the U.S. Food and Drug Administration (FDA) for only 3 years, there is new evidence suggesting that it’s safe and effective to use for at least 4 years. The same is true for the 52mg levonorgestrel intrauterine device (LNG-IUD)—it’s FDA-approved to last up to 5 years but safe and effective to use for at least 6.

Why is prolonged use of the implant and LNG-IUD so important?

Despite the promise of the Affordable Care Act, hundreds of thousands of women will continue to have gaps in their health care coverage and limited access to contraceptives including the implant and IUD. For example, women in states not expanding their Medicaid eligibility criteria may remain uninsured.

Allowing women to use their implant or IUD for an extra year can mean major benefits for individuals and families. It can also mean big-picture societal benefits. Research around the world has shown that IUDs and implants help reduce unintended pregnancy, abortion, and poor health for mothers and infants. If a woman can use an IUD or implant for longer, it makes the method even more cost-effective and further reduces the economic burden of these public health problems.

What does the evidence say?

I am part of a team of researchers following nearly 300 women who have used their implant or LNG-IUD beyond the FDA-approved durations of 3 and 5 years, respectively. We just published findings showing that:

  • 123 women had used their implant for an additional year, and 34 for an additional 2 years. For these women, there were no pregnancies.

  • 108 women had used their LNG-IUD for an additional year, 20 for an additional 2 years, and 3 for an additional 3 years. For these women, only one woman became pregnant within a few weeks of the IUD expiration.

  • The contraceptive failure rates for both the implant and LNG-IUD in the year following their expiration are essentially the same as the rates for the current FDA-approved labels. The failure rate of the implant in the fourth year was 0 per 100 women years (95% CI 0 - 1.61). For the LNG-IUD, the failure rate was 0.51 per 100 women years (95% CI 0.01 - 2.82).

How do these methods keep on working?

Our study will not specifically investigate how these methods prevent pregnancy during prolonged use, but we are evaluating the amount of the implant’s active ingredient, etonorgestrel, in the blood of the women using that method. We know that part of the way the implant works is by preventing ovulation (the release of an egg). Previous research suggested that a minimum of 90 picograms of etonorgestrel per milliliter of blood is required to suppress ovulation. At the fourth year, women in our study had median etonorgestrel levels well above that threshold (170 pg/ml), meaning the implant probably just keeps working the same way to prevent pregnancy after the 3-year mark.

What about overweight or obese women? Can they keep using their implant?

We didn’t limit who could participate in our study by body weight. Women had a range of body mass indices, including <25 kg/m2 or “normal weight” (28%), 25-30 kg/m2 or “overweight” (22%), and >30 kg/m2 or “obese” (50%). We compared the levels of etonorgestrel in the blood across these groups of women and found no differences. With no documented pregnancies and reassuring blood levels of etonogestrel in this diverse group of women, we feel it is safe for women of all weights to use their implant for an additional year.

Colleen McNichols, DO, MSCI, is a gynecologist, family planning specialist, and clinical researcher at the University of Washington in St. Louis. She is committed to improving access to quality reproductive care for all women. Her research interests include novel ways of using IUDs and implants.
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