Key Facts about the Injection

The injection contains the hormone progesterone and works in three ways to prevent pregnancy from occuring. Depo Provera is the funded injection available in New Zealand.

• The effects of the injection will last for three months at a time.
• It can take up to 7 days to be effective.
• It does not protect you from STIs.

How it works

Pregnancy happens when sperm reaches an egg and fertlises it. The injection works in three ways to interrupt this process:

• It stops ovulation.
• It thickens the mucus around the cervix, which makes it harder for sperm to get through.
• It makes the lining of the womb thinner so that a fertilised egg cannot implant.

Pros & cons

• The injection is over 99% effective when injections are taken on time. If injections are not taken on time, this reduces the effectiveness.
• It doesn’t interrupt sex.
• Periods may be irregular, heavier, and longer or they may stop all together.
• It does not protect you immediately from pregnancy – it can take up to 7 days, depending on when you had the injection and your last period, so other contraception is required.
• It does not protect you from STIs.
• You will need to see a nurse or doctor every three (or twelve weeks) for the injection.

Where to get it

The injection needs to be given by a doctor or nurse who has been specially trained. There may be a cost for the appointment and injection every three months. Please check with your doctor or nurse. Click here to find your nearest service.

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The hormone in the injection is similar to progesterone, which is one of the two main hormones made by a woman’s ovaries during her normal cycle.

When a woman has Depo Provera, her body senses the presence of the hormone so that her own hormone production is ‘switched off’. Because of this, her ovaries will not release an egg and this is how pregnancy is prevented. This is very similar to how the Pill works. Depo Provera is also sometimes used in the treatment of endometriosis.

The injection works in three ways:

• It stops ovulation.
• It thickens the mucus around the cervix, which makes it harder for sperm to get through.
• It makes the lining of the womb thinner so that a fertilised egg cannot implant.

If you are having Depo Provera for the first time, your first injection should be given during the first 5 days after the start of your normal monthly period.

The injection is commonly given in the upper arm or buttock. No one can tell you are on the injection and there is nothing more you need to do before having sex.

Pros

There are loads of things about the injection that are good for your body as well as your sex life.

• The injection is over 99% effective.
• It doesn’t interrupt sex.
• The injection works for 12 weeks / 3 months. 
• It may reduce heavy periods and period pain.
• It can be used by some women who cannot use the contraception that contains oestrogen.
• The injection is not affected by vomiting, diarrhoea or antibiotics (like some methods).
• Depo Provera is also likely to cause some reduction in risk of ovarian cancer, endometrial (uterine) cancer, endometriosis and possibly pelvic infection.

Cons

Everyone worries about negative side effects, but for many people, they’re not a problem. 

• Periods may be irregular, heavier, and longer or they may stop all together.
• If you use the injection for a long time, there are some concerns that it can cause slight thinning of the bones by reducing bone mineral density (this usually recovers once the injections stop).
• It may take a while for your periods to return to normal when you stop having the injection. In some women, this can take 6 to 12 months. However, more than half will fall pregnant within 12 months and over 90 percent within two years.
• Some women may put on weight when they use Depo-Provera.
• It can cause some side effects including headaches, mood swings, breast tenderness and irregular bleeding. Because the injection can’t be removed from your body (like an IUD or implant) if you do have any side effects they are likely to last as long as the injection and for some time afterwards.
• It doesn’t protect you against sexually transmitted infections (STIs), so you will need to use a barrier method such as condoms.
• It can cause acne.
• There can be a very small risk of infection at the site of the injection.
• You will need to see a nurse or doctor to have the injection every 3 months. 

Where to get the injection?

The injection needs to be given by a nurse or doctor who has been specially trained. Visit your local doctor or nurse to find out more. There may be a charge for your appointment and the injection so make sure to ask when you get in touch.

Who can get the injection?

Depo Provera can be used by most women who do not have any serious medical problems and by many women who use other forms of contraception. It may also be suitable for women who cannot take the combined pill for medical reasons.

What happens at an appointment?

An appointment will typically include:

• A few questions about your medical and family history, to work out what would suit you best.
• The doctor or nurse will take your blood pressure and they will weigh you.
• The doctor or nurse may be able to give you the injection the same day.
• You will need to go back to the clinic at 12 weeks for your next injection. 

When can I have the injection?

You can have the injection at any time in your menstrual cycle if you are certain you are not pregnant. If you’re given the injection during the first five days of your period you will be protected against pregnancy immediately.

If you have the injection on any other day of your cycle you will not be protected for the first seven days, so you will need to use another method of contraception, like condoms. You may also be required to take a pregnancy test after the injection has been given.

What happens if I miss my next injection?

Follow-up injections must be given on time. If you think your next injection is late use condoms until you know that your contraception is definitely protecting you again.