Using a Mirena for Birth Control

Mirena is a form of contraceptive that releases hormones directly into the womb.

The technical term for this type of birth control is intrauterine system, or IUS. Mirena uses a synthetic hormone called levonorgestrel that mimics the action of progesterone, one of the main sex hormones in women. Although it’s mostly used as a form of birth control, Mirena is sometimes also used to stop abnormally heavy menstrual periods and to keep the womb lining from growing too much, which can happen when you take oestrogen hormone replacement therapy.

So How Does the Mirena Actually Work?

The hormone in Mirena, levonorgestrel, works by thickening the layer of mucus that covers the entrance to the womb. With a thicker layer, sperm has a much harder time entering the womb, and therefore it decreases the risk of fertilization.

It has another purpose too, giving it a twofold benefit for contraception. At a certain point each month, every woman’s uterus lining thickens to prepare it to receive an egg. Levonorgestrel prevents this from happening, so even if the egg is fertilized it won’t be able to implant itself on the womb’s inner wall. In some cases, the actual presence of the device, hormones aside, can prevent a woman from getting pregnant just by being there and disrupting the normal flow of the womb.

How Do You Get the Mirena?

Mirena has to be inserted either by a nurse or a doctor, so there’s no doing it at home with this one, ladies. You have to go through an exam first to make sure your womb is large enough and in the right location to hold the IUS, and they’ll make sure you’re not pregnant and that you have no current STD’s as well.  Some doctors will do this procedure in their surgery, others will put you under twilight sedation.

Ideally, Mirena should be inserted sometime during the first week of your normal menstrual cycle. The first day of your period is considered the first day of the cycle. It will immediately go to work as a contraceptive. You can have it inserted at any time of the month as long as you’re not already pregnant, but you will still need to wear a condom for the next seven days. If you just had a baby, you should wait six weeks before getting Mirena.

How Long Does Mirena Work?

Mirena works effectively for up to 5 years, before the hormones start to run out. You can get it removed at any time during that period if you wish, but after 5 years it won’t be effective as a form of birth control. If you want, you can have a new one inserted at the same time, keeping you safe for another 5 years.

Now, if you want to get rid of the Mirena device but still don’t have any desire to get pregnant, you should have it removed the first day or two of your period. Sperm can live in your vagina for up to seven days, so if you decide to get rid of the Mirena device at any other time you should keep using condoms for the next week.  The Mirena has a small ‘string’ which hangs just outside of the cervix so it is very easy for your Doctor to remove it.

Pros and Cons

• Very popular birth control method with 180 million women world-wide currently using the device.
• Great for women with heavy periods as reduces severity
• Lasts for five years before needing replacement.
• Insertion and removal of the device  can be painful
• It is possible for the device to detach which may lead to spotting
• Does not protect you against STI’s

Want More Information?

If you want to discuss the Mirena with other members of the community – click here to go to the Ask Stay at Home Mum Section.

For more information on Mirena check with your doctor or try these websites:

• Mirena Home Page
• The Womens.org
• Fact Sheet from Family Planning NSW

If you become concerned about your or anyone else’s health please seek immediate medical attention or go to our health hotlines and website post for further resources.

SAHM takes no responsibility for any illness, injury or death caused by misuse of this information.  All information provided is correct at time of publication.