Contraceptive Injection
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Depo is a contraceptive injection effective against pregnancy for 12 weeks.
What is it?
Depo Provera® and Depo Ralovera® are brand names of Depot Medroxyprogesterone Acetate (DMPA), which is a progestogen-only contraceptive injection. It is given into the muscle (usually the upper arm or buttock) every 12 weeks by a health professional. The hormone is slowly released into the body.
How does it work?
The contraceptive injection works in three ways:
- it stops the body from releasing an ovum (egg) ever y month (ovulation)
- it makes the mucus in the cervix (the entrance of the uterus) thicker, so sperm cannot get through
- it changes the lining of the uterus (womb)
How effective is it?
It is over 99% effective at preventing pregnancy and contraceptive cover will last for three months after each injection.
The contraceptive injection is effective immediately if it is given between day one (first day of bleeding) and day five of a woman's menstrual cycle. If it is given at any other time of the cycle, other back-up contraception should be used for the next seven days (e.g. condoms).
Who can use the contraceptive injection?
The contraceptive injection is suitable for women who:
- cannot take oestrogen (found in most oral contraceptives and the vaginal ring)
- have difficulty remembering to take daily contraception
- want to use a safe and effective method and prefer it to other methods available
- are taking regular medications that interfere with other types of hormonal contraception
The contraceptive injection is not suitable for women who:
- think they may be pregnant
- have had breast cancer within the last five years
- have severe liver disease
- have a past history of a depressive illness or post-natal depression
- have undiagnosed abnormal vaginal bleeding
- have had a heart attack or stroke
- may be distressed by abnormal or unpredictable bleeding patterns
- have a high risk of osteoporosis
- are unable to take progestogens
Advantages:
- may relieve menstrual symptoms (e.g. painful or heavy periods)
- many women do not get periods after they have had one or two injections (with some seeing this as convenient)
- is suitable for women who cannot take oestrogen
- is not affected by other medications
- is not affected by changes in body weight
- is not affected by stomach upsets (vomiting or diarrhoea)
- the date of the next injection is the only thing to be remembered
- does not affect a mother's ability to breastfeed and does not harm a breast-feeding infant. It may be recommended to wait a few weeks after giving birth before having the injection. This is to avoid confusion about any irregular bleeding that may be related to the birth.
Disadvantages:
- once the injection has been given it cannot be removed or cancelled - it has to wear off
- involves regular visits to see a health professional which can be inconvenient and costly
- some women experience side effects such as headaches, tiredness or mood changes
- some women will have a small amount of weight gain (on average, women gain 2kgs in the first year of use)
- some women experience a loss of libido (loss of interest in sex)
- irregular bleeding may occur for the first few injections. This is usually light bleeding and for a few days only. Prolonged heavy bleeding is uncommon.
- women may have slight loss of bone density while using this method. This appears to be mostly regained after the method is stopped. Talk to your doctor for more information.
Is there anything else I need to know?
The return of fertility is often delayed by approximately six months on average, but the effect on fertility is temporary. Studies have shown no evidence of any effect on future pregnancies.
To reduce the risk of developing osteoporosis, maintain a calcium-rich diet, do regular weight bearing exercise (low impact aerobics, weight training, walking or running) and avoid smoking.
If you are late for your next injection (i.e. more than 14 weeks since your last injection), it is important that you use another form of contraception (e.g. condoms) until your next injection.
The contraceptive injection does not protect against sexually transmissible infections (STIs).
Page last updated Mon, 08 Aug 2011 14:13
