Choosing a method of contraception can be a difficult task for many individuals and couples. There are many ways of preventing pregnancy, each suiting some people more than others.

A method that is proving popular with some women is an injection of a drug known as medroxyprogesterone acetate, commonly known as Provera. When used in a long-acting form, Depo-Provera, this provides reliable contraception for 3 months. After that, if contraception is still needed, the injection is repeated.

Depo-Provera is very similar to the natural female hormone progesterone. It works by stopping the ovary from releasing an egg. The release of an egg is known as ovulation and usually happens once a month. With no egg, pregnancy is impossible.

Its greatest benefit is that once the injection has been given, nothing more need to be done. Many other types of contraception fail for ‘human' reasons such as forgetting to take a pill, failing to put on a condom properly and so on.

The main disadvantage with Depo-Provera contraception is that, after an injection, it is hard to predict when ovulation will restart and fertility return. Although the injections are repeated every 3 months, it may take as long as 18 months after an injection before pregnancy is possible.

For this reason, Depo-Provera is not recommended as a contraceptive for those couples wanting short-term protection between having babies.

The other main problem with this form of contraception is that periods may be unpredictable and irregular. They are usually lighter and disappear completely in about half the women using this method for more than a year. Occasionally, vaginal dryness, reduced libido and weight gain will happen as side effects of the hormone.

For those who do not wish to become pregnant for quite some time, Depo-Provera is a highly reliable contraceptive. One injection and the issue can be forgotten for 3 months.