Mirena is an intrauterine device, or IUD, produced by Bayer Pharmaceuticals. It is a soft plastic IUD that slowly releases a hormone called levonorgestrel into the uterus for up to five years. This device is over 99 percent effective, but pregnancies that do occur are miscarried 50 percent of the time, according to the "Women's Encyclopedia of Natural Medicine." Consult your physician to determine if Mirena is right for you.
How Mirena Works
Your physician implants the Mirena IUD into your uterus. Mirena then works by secreting levonorgestrel, a progestin that is used in birth control bills as well as IUDs. Mirena works in a variety of ways. In addition to the levonorgestrel, it may thicken the cervical mucus, which prevents sperm from entering the uterus. It may also thin the uterine walls and prevent ovulation. Mirena will not prevent sexually-transmitted diseases or infections.
Pregnancy on Mirena
Mirena, like other IUDs, can irritate the lining of the uterus, which prevents pregnancies from being carried successfully. In addition, the level of levonorgestrel may cause the pregnancy to become unsustainable, and the IUD itself might implant in the fetus and affect its development. Pregnancies that occur on Mirena may also become ectopic, which means that the embryo implants in the fallopian tube. However, if your doctor removes the Mirena IUD as soon as possible after you realize that you are pregnant, your risk of miscarriage may drop to 20 to 25 percent, according to an article published in 2007 in the "Middle East Fertility Society Journal."
What to Do If You Become Pregnant
You may have difficulty knowing if you are pregnant on Mirena because many women stop menstruating entirely while using the device. However, if you have a positive pregnancy test or if you suspect that you are pregnant, contact your physician immediately. Your physician can assess whether the pregnancy is viable. In addition, your physician will need to remove the Mirena IUD due to the risk of complications such as miscarriage, premature birth, infection and birth defects from the hormones in Mirena.
Only you and your physician can determine whether Mirena or any birth control device is right for you. The risk for miscarriage is high if you should become pregnant, and a pregnancy on Mirena can have serious consequences for both you and your fetus, as noted in "The Complete Guide to Hysterectomy." You may lose the pregnancy and/or your fertility as a result of the pregnancy. Complications can also be fatal. However, Mirena has many other benefits such as the fact that it can last up to five years and it is removable. Consult your physician to learn more about all of your options.