Birth control and you The Mirena

THE Mirena is a soft, flexible levonorgestrel-releasing intrauterine device that is inserted in a woman to prevent conception for up to five years. The T-shaped device is generally inserted by a doctor and works by releasing progestin.

According to obstetrician/gynaecologist Dr Charles Rockhead, the Mirena secretes about 20 micrograms of progesterone in 24 hours when it is placed in the cervix.

"So it has advantages beyond contraception. Sometimes it's good for patients who have haemorrhaging or heavy bleeding. It's good for patients who have adenomyosis (when endometrial tissue, which normally lines the uterus, exists within and grows into the muscular wall of the uterus) and some people who have fibroids," he said.

Mirena changes the cervical mucus so that it's harder for sperm to pass through the cervix. It starts working as soon as it is inserted; however, it's advisable that you wait 24 to 48 hours before having sexual intercourse.

It takes only a few minutes to insert the device and this is generally placed in your uterus about seven days after your period has started.

"The cervix is usually open, and the more babies you deliver vaginally the more open it is, so it's an easy insert," said Dr Rockhead. "However, for a patient who has done a C-section and has never delivered vaginally, the cervix is very tight, so the insert is going to be a little painful."

He pointed out that, while the Mirena generally costs about $17,000, the fact that it offers protection against pregnancy for up to five years makes it more cost-effective than several other birth control options. When calculated, it would cost about $250 per month. It is also better than the Copper T, which in the early days was generally associated with painful periods and heavy bleeding.

Here are some of the other advantages of the Mirena.


1. It helps to decrease menstrual cramps and pain.

2. It is one of the most effective long-term reversible contraceptive methods.

3. Once removed, fertility returns.

4. It helps to protect against ectopic pregnancies.

5. It can be used by post-menopausal women doing oestrogen therapy to minimise the risks of endometrial cancer.

6. It does not cause any interruption to foreplay or sexual intercourse.

7. It can be used while breastfeeding.


1. It affects your menstrual cycle.

2. Mirena does not protect against sexually transmitted diseases.

3. Because Mirena releases low dosages of progestin in the bloodstream, it causes weight gain and acne in a small number of women.

4. It will cost a lot to have it initially implanted.

5. You will have to go to a health professional to have it inserted and removed.