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How does it work?Depo-Provera injection contains the active ingredient medroxyprogesterone acetate, which is a synthetic form of the naturally occurring female sex hormone, progesterone.
Depo-Provera injection is as a long-term form of contraception. It is usually given into the muscle of the buttock or upper arm. The injection produces a reservoir of medroxyprogesterone in the muscle, which is then continuously released into the bloodstream over a period of 12 weeks.
The medroxyprogesterone prevents pregnancy in three main ways. Firstly, it prevents eggs from being released from the ovaries (ovulation). It also increases the thickness of the natural mucus at the neck of the womb, making it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of any eggs that are released is less likely. The hormone also changes the quality of the womb lining (endometrium), making it less receptive for any fertilised eggs to implant into.
The contraceptive effect of the injection lasts for three months. The first injection should be given in the first five days of a normal menstrual cycle (day one is the first day of your period). This will protect you from pregnancy immediately. The injection can also be given at any other time in your cycle if your doctor is sure that you are not pregnant, but you will need to use additional contraception, eg condoms for the first seven days after having the injection. Further injections should be given every 12 weeks to provide continued contraception.
For women who are using this method of contraception after having a baby, the injection should be given within the first five days after the birth if you are not breastfeeding. However, if it is given within this time you should aware that there is an increased risk of heavy and prolonged bleeding. If you are breastfeeding, you should not be given the first injection until at least six weeks after the birth. Again, further injections should be given every 12 weeks to provide continued contraception.
If you have had a miscarriage or abortion at under 24 weeks, you can have this injection immediately after and you will be protected against pregnancy straight away.
If you have the injection more than seven days after the miscarriage or abortion, you will need to use extra contraception to prevent pregnancy for the first seven days after having the injection.
The injection can be used on a short-term basis for partners of men having a vasectomy (to provide protection until the vasectomy becomes effective), for women who are being immunised against rubella (to prevent pregnancy during the period of activity of the virus) and in women awaiting sterilisation.
It is very important that you discuss the pros and cons of this form of contraception with your doctor before you are given the injection, particularly with regards to having children after stopping the injections. Fertility does return once the injections are stopped, but the time varies from one women to the next. Most women should start to ovulate 5 to 6 months after their last injection, but may not conceive until 10 to 15 months after their last injection (or sometimes even longer). You should also be made aware of the potential side effects, as the injection cannot be reversed once it has been given.
What is it used for?
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Contraception
Warning!
- It is very important that you discuss the pros and cons of Depo Provera with your doctor before you are given the injection. The injection cannot be reversed once it has been given and its effects (which may include any unwanted side effects) last for at least three months.
- All women should be counselled by their doctor prior to using Depot Provera about the delay in being able to have children once the injections have stopped. Some women may not be able to conceive for 10 to 15 months after having their last injection.
- This contraceptive usually disrupts the menstrual cycle. It may cause irregular bleeding or spotting, heavy or prolonged bleeding, or your menstrual bleeds to stop alltogether. If you experience menstrual bleeding that is heavy or prolonged should inform your doctor.
- There is a tendency for women to put on weight while on Depo Provera. Ask your doctor for more information.
- Depo Provera decreases oestrogen levels. Over time, this can cause a loss of bone mineral density and increase the risk of osteoporosis. This is particularly important for adolescents and young women whose bones might not yet be fully developed, as it is unknown if the injection will lower their peak bone mass and hence increase the risk of osteoporotic fractures later in life. There is ongoing research to determine this. Adolescents should therefore only use Depo Provera after all other contraceptive methods have been discussed and are considered to be unsuitable or unacceptable. Women of all ages who want to continue using the injection for more than two years should only do so after all the risks and benefits have been re-evaluated.
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