What is it?
Mirena is a hormonal intrauterine device (IUD) that’s inserted into the uterus for long-term birth control. It can be left in the uterus for up to 5 years. It’s a small T-shaped plastic frame that releases a type of progestin hormone called levonorgestrel into the uterus. Most of the hormone stays locally inside the uterus, only small amounts of the hormone are measured in the blood after insertion. Mirena does not contain estrogen.
Mirena was approved by the FDA for use in the United States in 2000 for birth control as well as to treat heavy periods.
How does it work?
There is no single explanation for how Mirena prevents pregnancy. We know that Mirena may thicken the cervical mucus to prevent sperm from entering the uterus. It may inhibit sperm from reaching or fertilizing an egg. Mirena also thins the lining of the uterus and partially suppresses ovulation. Most likely, the above actions work together to prevent pregnancy. It is over 99% effective.
What do women like about Mirena?
Mirena is one of the most effective forms of birth control. After insertion by a healthcare professional, it works consistently for up to 5 years. So, you don’t have to think about birth control every day or even every year! Most women also like having shorter, lighter, less painful periods. A percentage of women will stop having periods with Mirena, so it’s important to decide if that is something you would be comfortable with.
Mirena can be removed at anytime. You can have it removed by your healthcare provider whenever you want to try for pregnancy. Within a year of having Mirena removed, approximately 8 out of 10 women succeed in become pregnant. It can also be used while breast-feeding. After 5 years of use, Mirena can be removed and another one inserted if pregnancy is not desired.
The most common side effects are headache, acne, breast tenderness, breakthrough bleeding, absence of periods (especially after one year of use), mood changes, weight gain, ovarian cysts, and abdominal pain. It’s also possible to expel Mirena from your uterus. You may be more likely to expel Mirena if you have never been pregnant.
No one birth control is right for everyone. There are risks associated with Mirena as well as other birth control methods. Since there is only a small amount of hormone released into the bloodstream, we do not see women complaining of decreased libido with Mirena. It also appears that lubrication isn’t affected either. If anything, we have noticed some women saying their libido has improved simply because they do not have to worry about pregnancy anymore and can be more spontaneous about when and where they are going to have sex. If you are remotely interested in Mirena, I encourage you to have a conversation with your healthcare provider. Although there is a slight increase for expulsion in nulliparous women, an experienced healthcare provider can safely insert Mirena. Ultrasound guidance can also be used for proper placement.