by Libbie Reed

Created on: May 04, 2008

Emergency contraception comes in the form of a single dose of progestogen which, if taken a short time after unprotected sex, can prevent pregnancy. Sometimes referred to as "the morning after pill" this type of contraception should not be used as a regular form of birth control, but rather as a means of preventing pregnancy when other methods have failed (i.e. a split condom) or when contraceptive precautions have been overlooked.

The "morning after" pill is a high dose of progestogen and works in three ways:

1. It can prevent ovulation if this has not already occurred.

2. It thickens the mucus which is secreted at the neck of the womb making it harder for sperm to penetrate.

3. It thins the lining of the womb making it harder for a fertilized egg to implant itself.

This form of contraception is by no means foolproof and its effectiveness is dependent upon how soon after unprotected sex it is taken. For a 95% chance of preventing pregnancy the "morning after pill" should be taken with 12 to 24 hours and whilst this pill can be taken up to 72 hours after unprotected sex, the effectiveness is reduced to around 60%.

The emergency contraceptive pill will only offer protection from unwanted pregnancy once, after unprotected sex and will not offer protection for the remainder of a menstrual cycle.
However, it is possible to take this type of pill more than once, if necessary, during a cycle.

There are few side effects from the emergency contraceptive pill and these most commonly include nausea, abdominal pain and irregular bleeding. Some women are reported to have experienced headache, dizziness and vomiting but these symptoms affect only 1 in 10 women. If vomiting occurs within 3 hours of taking this type of contraceptive it will most likely not have been fully absorbed and it may be necessary to take another pill.

Because the "morning after pill" reduces the thickness of the lining of the womb there is an increased risk of ectopic pregnancy. This is where a fertilized egg implants itself in a fallopian tube. If pregnancy is suspected despite taking this pill it is important to see a GP to rule out the possibility of an ectopic pregnancy.

The emergency contraceptive pill is believed to be safe for breast feeding mothers. Although small amounts of progestogen will pass into the breast milk it is not thought to be harmful to the baby.

There are a few medicines which might interact with the emergency contraceptive pill so a GP or pharmacist should be consulted if other medications are being taken. However there are no known interactions between this type of contraception and alcohol.

The only other type of emergency contraception available is the IUD (intra-uterine device) which is a copper device inserted via the vagina into the womb. If an IUD is fitted within 5 days of unprotected sex this will prevent pregnancy. However, this is a far less convenient method of emergency contraception since the procedure involves an internal examination to determine the size of the womb before a device can be inserted.

An IUD works by releasing copper into the body. The copper causes an increase in white blood cells in the cervix which kill the sperm in the cervix, womb or fallopian tube. The device also makes it harder for a fertilized egg to implant itself in the womb although it is not fully understood why.

Once in place, an IUD will continue to provide contraceptive protection for up to ten years, although annual check ups are necessary to ensure that the device is still properly in place and has not caused any type of infection.

Of course neither the "morning after" pill or an IUD offer protection from sexually transmitted diseases.

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