Enlarge this image

The best time to get pregnant (see Maya's popular ovulation calculator to calculate when you are most likely to ovulate and is most fertile)

You're most likely to get pregnant if you have sex during the seven days before you ovulate. This is usually about 12 days after the first day of your last period.

An egg lives for about 12–24 hours after it's released. For pregnancy to happen, the egg must be fertilised by a sperm within this time. Sperm can live for up to seven days inside a woman's body. So if you've had sex in the seven days before ovulation, the sperm will have had time to travel up the fallopian tubes to 'wait' for the egg to be released.

It's difficult to know exactly when ovulation happens, unless you're practising fertility awareness (see External links). But in most women, ovulation usually happens 10-16 days before the start of the next period. The menstrual cycle is counted from the first day of a woman’s period (day one). Some time after her period she will ovulate, and then 10-16 days after this, she'll have her next period. The average cycle takes 28 days, but shorter or longer cycles are normal.