Contraceptve injections

Written by Dr David Delvin, GP and family planning specialist



Worldwide, many millions of women use the contraceptive injection. In its early years (back in the 1970s and 1980s), this injection was highly controversial. That was partly because of the thoughtless way in which some doctors had used it – often giving it to poorer women, especially those from ethnic majorities, without really explaining the nature of the drug.

In addition, many women who received it were not warned that it tends to disturb the periods very markedly (see 'What are the side effects?' below).

But these days, many people do make an informed choice to use 'the jab' – or 'the jag,' as it is known in Scotland. The majority of them are very happy with it, and a lot are simply not interested in changing to any other method.

Nonetheless, the method is not ideal for everyone. Before you agree to have it, please bear in mind the saying, 'Once it's in, it's in'.

In other words, once it has been injected, no one can suck it out again! And in the case of the most commonly-used version of 'the jab,' it will be a good three months before the drug has vanished from your body. So be sure that you really do want it.

What are contraceptive injections?

These jabs contain hormones. When injected into a muscle (usually in the buttock), the medication keeps you from getting pregnant – for a considerable period of time. So a very good thing about it is that you don't have to remember to keep on taking anything, which makes this method very useful for the many people who forget Pills!

Also, the jab does ensure that sex is spontaneous; you don't have to bother about putting on condoms, or inserting chemicals. Quite a few women regard this as a 'plus'.

In Britain, there are currently (2005), just two types of contraceptive jab available. They are:

Depo-provera, which is by far the more commonly-used. It protects you – almost fully – against pregnancy for 12 weeks.

Noristerat - which provides contraceptive protection for eight weeks.

Both these jabs contain a type of hormone called a 'progestogen' – which has similar effects to the natural female hormone progesterone.

In the USA and in certain other countries, there is another type of contraceptive jab which (like the Pill) contains two hormones. It is called 'Lunelle' and the idea behind it is that it should control the periods better than Depo-Provera and Noristerat do. There are plans to bring it to the UK – possibly in 2006 or 2007.

How do these contraceptive jabs work?

They have three useful anti-fertility effects.

They stop you from ovulating (producing eggs).

They thicken the mucus in your cervix – making it difficult for sperms to get through.

They make the lining of your womb thinner, so that if an egg (ovum) became fertilised, it would have difficulty attaching itself to the lining.

How effective are these injections?

They are very efficient indeed. Most experts rate them as around 99 per cent effective, which means that if 100 women used the jab for a year, only about one would become pregnant. This makes the injection one of the most efficient of all contraceptives.

However, you do have to remember to turn up for your next injection. Many of the pregnancies which occur in people who are 'on the jab' happen because somehow the injection doesn't get given on time.

Also, please bear in mind that a few prescription medicines can interfere with the efficiency of the jab. Your doctor or nurse should give you fuller details, but if you prescribed other medications by a doctor, it's always best to mention that you are 'on the jab'.

In practice, it is chiefly medicines for epilepsy and for tuberculosis that can interfere with the working of the contraceptive injection.

What are the advantages of the injection?

Firstly, there's the fact that the only action you have to take is to turn up for your jabs on time.

Secondly, it now (2005) seems probable that Depo-Provera gives you some protection against cancer of the womb lining. Balanced against that is the fact that there is still a chance that it might increase the chances of breast cancer.

Both of the jabs which are used in Britain are thought to help protect you against:

ovarian cysts

ectopic pregnancy.

What are the side effects?

Don't let anyone give you the idea that the jab is without side effects! In particular, there is a very high chance (40 per cent) that your periods will be disrupted in some way.

For Depo-Provera (medroxyprogesterone acetate or DMPA), the commoner side-effects are as follows:

heavy periods

prolonged periods

irregular or infrequent periods

absent periods – though many women are very grateful for this effect

headache

tummy ache

weakness

dizziness

weight gain

delayed return of fertility after stopping the jab – however, there's no evidence at present (2005) of long-term infertility.

There are other (rarer) side-effects, and you should talk these over with the doctor or nurse before you start, and read about them in the leaflet which you'll be given.

The more rarely used injection Noristerat (norithisterone enantate) has similar side effects, and also may sometimes cause breast tenderness or reactions at the injection site.

Is there anyone who shouldn't have the jab?

Yes. Neither jab is suitable for women who are already suffering from undiagnosed abnormal vaginal bleeding.

Nor should you have the injection if you've had a hormone-dependent cancer. It may not be suitable for you if you have migraine, liver problems, or a history of thrombosis (clots). There are certain rare conditions in which use of the injection is ruled out, but your doctor will advise you if this applies to you.

Also, if during a pregnancy you've ever had the condition of cholestatic pruritus (intense itching), then the jab is not for you.

Finally, it has been suggested that regular use of the jab may lead to 'thin bones' (osteoporosis). As at 2005, this is still not certain. But if you already have osteoporosis, then I think it would be better for you to choose some other form of contraception.

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