Ovulation is the term used to describe the release of the ovum (egg) from a woman's ovary. This occurs about once a month, about 14 days before a period. Depending on the length of your cycle, the day that you ovulate will vary. You need to be ovulating to get pregnant. Sometimes people think that because their periods haven't started yet they cannot be ovulating BUT beware - you do usually ovulate before your first period! Therefore you can get pregnant if you have sex even before your periods start.