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Written by Dr David Delvin, GP and family planning specialist
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Worldwide, many millions of women use the contraceptive
injection. At the moment, about 3% of British women of reproductive age use it.
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.
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'. You should be counselled about the jab’s side-effects
and given a leaflet about its mode of action.
In the case of the most commonly used version of the jab, it’ll
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.
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.
There are currently just two types of contraceptive jab
available in Britain. They are:
-
Depo-provera (medroxyprogesterone),
which is by far the most commonly used. It protects you – almost fully –
against pregnancy for 12 weeks
-
Noristerat (Norethisterone), which
provides contraceptive protection for eight weeks. In practice, it is mainly
used ‘short-term’ in Britain – for instance, in women whose partners are
awaiting a
vasectomy.
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 that, 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 2009 or 2010.
Who shouldn’t use contraceptive injections?
Neither jab is suitable for women who are already suffering
from undiagnosed abnormal vaginal bleeding.
You shouldn't have the injection if you’ve had a
hormone-dependent cancer, and 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.
The Committee on Safety of Medicines have issued the following
advice about the use of the jab.
-
In adolescent girls, it should be used only where other methods
are inappropriate.
-
In women of all ages, the benefits of using the jab for more
than two years must be evaluated against the risks.
-
In women with risk factors for
osteoporosis, other
methods should be considered, as it is possible that regular use of the jab
causes a reduction in bone mineral density.
How do 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
sperm 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 that 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’s chiefly medicines for
epilepsy and
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 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 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, the more common side-effects are as follows:
-
heavy periods
(menorrhagia)
-
prolonged periods
-
irregular or infrequent
periods (oligomenorrhoea)
-
absent periods – though many women are very grateful for this
effect
-
headaches
-
tummy ache
-
weakness
-
dizziness
-
weight gain
-
delayed return of fertility after stopping the jab – however,
there’s no evidence at present 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 you’ll be given.
Noristerat has similar side-effects, and may cause breast
tenderness or reactions at the injection site.
Where can I get the injection?
Traditionally, the jab has mainly been given by the
contraceptive experts – that is, doctors and nurses at family planning clinics.
But these days, more and more GPs are prescribing contraceptive injections in
their surgeries.
Usually, the drug is started during the first five days of your
period – because this gives you immediate protection against pregnancy.
However, quite often the jab is given postnatally – that is, by
the staff of the Obstetric Department, after you’ve had a baby.
Very commonly, you have the injection about six weeks after
giving birth. Having the injection any earlier than this seems to be more
likely to cause problems with heavy bleeding.
If you are hoping to
breastfeed, you
should definitely not have the jab until your baby is at least six weeks old.
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Last updated 21.08.2008
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