Ovulation is when a mature egg from your ovary is released into your fallopian tube, and is available for fertilization by sperm. Approximately every month an egg will mature within one of your ovaries. Ovulation occurs 12-16 days from the first day of the menstrual period and usually lasts between 12-24 hours. It is important to be aware of ovulation because that’s when a woman is most fertile and has the highest probability of conceiving. Note: Because sperm can live inside a woman’s body for up to five days, if intercourse, sexual activity, artificial insemination or IVF occur three or four days before ovulation there is still a chance that the egg may get fertilized.