Contraception (birth control) is essential if you are having sex but do not want to have a baby. It stops sperm from fertilising an egg. Some types of contraception can also protect you from sexually transmitted diseases or infections (STDs or STIs).

A woman can get pregnant the first time she has sex, even if the man ejaculates outside her vagina.

It is important to sort out what kind of contraception is the best for you before you need it, and to make sure you are protected. It's too late to start thinking about it when you are already in a sexual situation.

No matter what method of contraception you choose, you should also use condoms if you have a new partner, several partners (or your partner does) or if you or your partner have an STI.

How does contraception work?

During sex (intercourse), when a man climaxes (ejaculates), his sperm flow into the woman's vagina. They swim up through her womb (uterus) and into the fallopian tubes where her eggs are. Fertilisation happens if an egg is there and a sperm joins with it. The fertilised egg will then travel back down the tube and into the womb, where it buries itself in the lining and develops into an embryo. Over the next nine months, a baby will grow in the womb. If fertilisation does not happen, the lining of the womb comes out each month as blood (a period). Each different type of contraception stops this process from happening in a different way, at a different time.

How do I choose the right method for me?

You need to consider the following:

• how important it is that you don't get pregnant
• whether you need protection from STIs
• how often you are having sex
• how effective each method is
• what it costs
• how easy it is to find/buy/have fitted
• how comfortable and secure you feel with it
• whether your partner accepts it
• whether you have any medical conditions that may affect your choice. For this, you may need to know your family's medical history, particularly if you are considering taking the contraceptive pill.

See: Contraception methods

Original material provided by Auckland Sexual Health Service. Edited by everybody.