Mirena (levonorgestrel-releasing intrauterine system) is a hormone-releasing system and type of IUD (intrauterine device) that is placed inside your uterus to prevent pregnancy for as long as you want for up to 5 years. Mirena emits hormones into your uterus directly. The hormones stay in the uterus and are not systematic, meaning they do not go to other parts of your body. This is why it won’t cause significant weight gain like oral contraceptives sometimes do or increase breast tenderness. Another bonus is that the Mirena might also shorten, lighten, or even eliminate periods altogether while you use it.

OK, but how does Mirena work?

The small amounts of levonorgestrel released by Mirena make your cervical mucus thick and tacky so sperm can’t swim through it. If the sperm gets in, then they can’t make it to the egg to fertilize it. Another way the Mirena, or IUDs in general, prevent pregnancy is it promotes the production of white blood cells and when a foreign object is placed inside the uterus; your body creates these white blood cells to defend itself. So when you have sex, if sperm does make it through your tacky mucus to your uterus, the white blood cells will attack them.

Mirena is 99.9 percent effective at preventing pregnancy and like metal IUDs, it needs to be fitted and removed by a medical professional, but once it’s in place, that’s it, you’re done, no fuss, no muss!

Mirena isn’t for everyone

Only you and your healthcare provider can decide if Mirena is right for you.

  • Mirena may be a good choice if you already have at least one child and
  • You want to have more children…someday
  • You’re happy with the size of your family
  • You’re not sure if you want more children
  • You recently had a baby (6 weeks ago or more) and you’re looking for birth control that fits your needs.

Mirena should not be placed earlier than 6 weeks after you give birth or as directed by your healthcare provider. If you are breastfeeding and plan to continue breastfeeding after Mirena is placed—be sure to tell your healthcare provider.

Women's Center for Integrative Health
354 Broad Street
Eatontown, NJ 07724
Phone: 732-542-3800
Fax: 848-456-4476
Office Hours

Get in touch