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The Mirena IUD is growing in popularity because it can protect against pregnancy for up to 5 years. But women may also suffer from severe side effects. These side effects led women to file lawsuits against Bayer.

What is Mirena?

Mirena is a type of long-acting, reversible birth control called a hormonal intrauterine device (IUD) and is manufactured by Bayer Pharmaceuticals. An IUD is a small, flexible, T-shaped device that is implanted in the uterus. Mirena uses levonorgesterel– a progestin birth control hormone–and slowly releases a small amount into the uterus over time. Because it releases hormones directly into the uterus, it releases a lower level of hormones into the body than oral contraceptive pills.

It was approved in 2000 by the Food and Drug Administration (FDA) and is one of two hormonal IUDs approved for use in the United States. In 2009, the FDA expanded Mirena's approval to treat heavy menstrual bleeding in women already using an IUD. It is more than 99 percent effective in controlling pregnancy for up to 5 years, at which point the implant must be replaced. Mirena is recommended for women who have had a child.

Globally, the IUD is the most popular form of reversible birth control with an estimated 150 million users. In the United States, the IUD's popularity is growing and it made up about 10.4 percent of the contraceptives issued by doctors in 2011, up from 1.4 percent in 2002. Mirena must be inserted by a medical provider and usually costs about $800.

Mirena is more convenient and effective than most oral contraceptives because once it is implanted women don’t have to worry about taking a daily pill. The effectiveness of oral contraception relies on "perfect use," meaning women must faithfully take their birth control daily. Oral contraceptives have a failure rate as high as 30 percent because they are not taken perfectly, while Mirena has a failure rate of less than 1 percent.

This device is highly effective at preventing pregnancy, but some women may experience dangerous, life-threatening side effects such as perforation of the uterus, pelvic inflammatory disease and ectopic pregnancy (pregnancy that occurs outside the uterus). The device may also spontaneously move from the uterus and embed in other parts of the body such as the uterine wall or abdomen, requiring difficult surgery to remove. Women who have experienced some of these side effects filed lawsuits against Bayer claiming that the company did not properly warn of these side effects.

What are Common Side Effects of Mirena?

Common side effects of Mirena include:

One of the most dangerous side effects of Mirena occurs when the device migrates from its normal position in the uterus. Despite the fact that Bayer claims this is a rare occurrence with Mirena, a study published by the Department of Radiology at the Ronald Reagan UCLA Medical Center found that this is a "frequently encountered complication." When the IUD migrates, it can perforate the uterus and enter the abdominal cavity, pelvis, bladder or blood vessels. It can cause pain, infection, and damage to intestines and other nearby organs. This is a serious condition and requires surgery to correct. In some cases, emergency surgery is necessary to prevent further damage.

In order to locate the device, radiologists use an ultrasound or X-ray. In some cases, women have had to undergo several surgeries because the device is difficult to locate and remove. The risk of perforation of the uterus is also increased in women who use Mirena immediately after delivering a child, and the risk is elevated for at least 6 months after delivery.

How Does Mirena Work?

Mirena works by slowly releasing 20 mcg of levonorgestrel into the uterus each day. Throughout the course of 5 years, this dose decreases while still remaining effective. In contrast, birth control pills typically release 150mcg into the body. The dose of hormones is higher in oral contraceptives because they must first be digested before the hormones can become effective and act on the uterus. Mirena works by directly releasing the hormone into the uterus.

While the exact way in which Mirena works is not known, Mirena may work in one or more of the following ways:

  • Thickening the mucus on the cervical wall to prevent sperm from entering the uterus.
  • Altering the wall of the uterus.
  • Inhibiting survival of sperm.

Because Mirena thins the lining of the uterus, it also decreases menstrual bleeding. After the device is implanted, the woman doesn’t need to do anything to prevent pregnancy for up to 5 years.

Removing Mirena

When it is time to remove the device, the health care provider removes it by using the attached string. The arms of the device are flexible and bend up as the device is removed. However, sometimes the device can migrate outside of the uterus or become lodged in the uterine wall. When this happens, the device must be removed surgically. Another device can be implanted if the woman wants to continue to prevent pregnancy.

Clinical Studies

In two large clinical trials, Mirena proved to be extremely effective in preventing pregnancy. In the studies, 1,169 women 18-35 years of age used Mirena for up to 5 years. The pregnancy rate over the 5 years was 0.7 per 100 women, or 0.7 percent. After Mirena was removed, 80 percent of women who wanted to become pregnant were able to do so within a year after removing Mirena.

Pregnancy Risks & Other Serious Side Effects

Pregnancy complications

If a woman becomes pregnant with Mirena, doctors recommend surgically removing the zygote immediately. Otherwise, the patient can experience a septic abortion, a condition in which the uterus becomes septic, endangering both the patient and the pregnancy. Mirena can also cause miscarriage, premature delivery and sepsis.

woman crying

Ectopic pregnancy

Of the women who become pregnant while using Mirena, half are ectopic pregnancies, which occur when an egg becomes fertilized outside of the uterus. It is often referred to as a “tubal pregnancy,” since it commonly occurs within one of the fallopian tubes. An ectopic pregnancy threatens the life of the mother. Women who have ectopic pregnancies often undergo surgery to remove the fertilized egg (zygote) and may become infertile.

ectopic pregnancy illustration

Pelvic inflammatory disease

A bacterial infection that affects the female reproductive system can often result in pelvic inflammatory disease (PID). PID can cause infertility by damaging the uterus, ovaries and fallopian tubes. This condition can occur within three weeks after insertion of Mirena. The FDA warns that women with a history of PID should avoid Mirena and all IUDs.

woman in pajamas holding stomach

Device expulsion

The device may also be spontaneously expelled from the body. During this time, the woman is unprotected from pregnancy. This occurs in about 6 percent of Mirena users. Some symptoms of a possible device expulsion include cramping, bleeding or spotting, pain during sexual intercourse, lengthened or absent device strings. Women who have never given birth are at higher risk for device expulsion.

female reproductive system and mirena

Mirena Lawsuits

Lawsuits filed against Bayer Pharmaceuticals, Mirena's manufacturer, claim that the company is guilty of failure to warn the public that the device is prone to spontaneous migration and perforation of the uterus. A number of women claim that the drug manufacturer knew of the dangerous risks and released a defective product.

Because they claim Bayer willfully endangered them, they are suing for punitive damages in addition to compensation for medical costs, lost wages and pain and suffering caused by Mirena. Plaintiffs also accuse Bayer of using misleading advertising, concealing the harmful side effects and misrepresenting the benefits of Mirena. Contacting an experienced Mirena attorney can help you to determine if you have a claim against Bayer Pharmaceuticals.

Nearly 500 federal Mirena lawsuits were consolidated in multidistrict litigation in the Southern District of New York (In Re: Mirena IUD Products Liability Litigation, MDL Docket No. 2434, JPMDL). U.S. Judge Cathy Seibel will oversee the process.

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