A new study finds that women who left Mirena IUDs in their bodies beyond the FDA-approved time period remained infertile for up to a year longer than the approved duration.

Medical researchers at the Washington University School of Medicine in St. Louis studied pregnancy rates among 263 women who left the Mirena IUD in for more than five years (the FDA-approved duration). Just 0.51 per 100 of those women became pregnant.

The study’s preliminary findings were published in the Obstetrics & Gynecology medical journal in February 2015. Researchers want to enroll 800 women before the ongoing study is concluded.

With the development of a hormonal IUD in the 1960s and 1970s, the long-term birth control devices became a popular option for women. Since the Mirena IUD’s approval by the FDA in December 2000, more than two million women in the United States, and more than 15 million women worldwide, use the birth control device.

Mirena IUD Complications Reported by Some Users

An IUD is a tiny T-shaped device inserted into the uterus by a doctor. It prevents an egg from fertilizing by damaging or killing the sperm. In 2010, IUDs accounted for 3.5 percent of women ages 15 to 44 who were using birth control.

The Mirena IUD is implanted into the uterus to provide protection against pregnancy for up to five years. It contains a steroid reservoir that releases levonorgestrel, a second generation progestin used in many forms of birth control, into the bloodstream. The Mirena is manufactured by Bayer AG.

But migraine-like headaches and progressive vision loss — a condition known as psuedotumor cerebri, or intracranial hypertension — have been reported by many women.

Pseudotumor cerebri (PTC) puts pressure on the optic nerve, resulting in blurred vision or temporary black-outs. Surgery may be required to relieve the pressure. The headaches are often concentrated in the back of the head and are reportedly most severe first thing in the morning or at night. Mirena headaches may be aggravated by changing position.

Vision problems can range from double-vision, blind spot, blurriness and loss of peripheral vision to blindness. Tinnitus, a ringing or “whooshing” sounds in the ear, has also been reported by women who use the Mirena IUD.

Mirena Lawsuits

Plaintiffs have accused Bayer of knowing of the link between levonorgestrel and intracranial hypertension but failing to warn of it. Other countries including South Africa and Hong Kong, the warning labels on Mirena disclose information about the risk.

A panel of federal judges rejected a request to centralize the proceedings of nine separate plaintiffs who asked that their Mirena lawsuits be centralized in a multidistrict litigation (MDL), which would have appointed a single judge to hear all the Mirena IUD lawsuits filed throughout the United States.

All Mirena IUD psuedotumor cerebri lawsuits will be heard in the district where they are filed.

There are some 600 Mirena lawsuits already centralized in the Southern District of New York for claims limited to women who allegedly suffered internal injuries as a result of Mirena migration, which is when the device moves out of place, punctures the uterus and migrates to other areas of the body. In addition to Mirena migration causing internal injuries and infections. In these cases, it can leave women unprotected against unwanted pregnancy.