You're most fertile when an egg is released from your ovaries (ovulation). Read more about having regular sex to get pregnant, your menstrual cycle and ovulation.
You're most fertile within a day or two either side of an egg being released from your ovaries (ovulation).
But you can get pregnant if you have sex at any point during the week before ovulation, as sperm can live inside a woman's body for up to seven days.
If you're hoping to get pregnant, you don't need to specifically plan sex around this time though.
It can be difficult to work out exactly when you ovulate and trying to have sex to a schedule can cause unnecessary stress and anxiety – and may mean you actually end up having less sex.
For the best chance of getting pregnant, have sex every two or three days throughout your cycle.
Read more about the signs of ovulation and getting pregnant.