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How Mirena^® Works

Mirena (levonorgestrel-releasing intrauterine system) slowly releases very small amounts of the hormone levonorgestrel directly into your uterus.

There is no single explanation for how Mirena works. Mirena may:

• Thicken cervical mucus to prevent sperm from entering your uterus
• Inhibit sperm from reaching or fertilizing your egg
• Make the lining of your uterus thin

Mirena may stop the release of your egg from your ovary, but this is not the way it works in most cases. Most likely the above actions work together to prevent pregnancy. Like other forms of birth control, Mirena is not 100% effective.

Mirena keeps hormone levels steadier and lower than the Pill.

What Mirena looks like

Mirena is a tiny T-shaped piece of soft, flexible plastic that is placed in the uterus by your health care provider during an office visit. It's designed to be small and comfortable, so that you and your partner most likely won't even feel like it's there.