A woman determines her fertile days by tracking her menstrual cycles and pinpointing when she ovulates, says the American Pregnancy Association. This can be done through different methods, including using ovulation predictor kits and keeping an ovulation calendar.
Ovulation often occurs between days 11 and 21 of a cycle, though some women ovulate later, notes the American Pregnancy Association. Tracking ovulation is done with test strips similar to home pregnancy tests, but women should look for signs of ovulation. Another method is to use an ovulation monitor.
Ovulation occurs when the ovary releases a mature egg, and it moves down the fallopian tube, according to the American Pregnancy Association. Once this happens, the egg is ready to be fertilized. With most women, one egg from one of the ovaries matures and is released. After going through the fallopian tubes, it waits to be fertilized by sperm. If this doesn’t happen, the uterine lining sheds, and menstruation begins. The most fertile period is around the time of ovulation, usually a few days before and after it happens.
Once an egg leaves the ovary, it lives for up to 24 hours, says the American Pregnancy Association. However, it is a good idea to have live and healthy sperm waiting when the egg is released so they can reach the egg before dying and while the egg is still alive. Tracking ovulation is one of the best ways to find the fertile window and have sexual intercourse at the right time.