Then, the egg moves through a tube toward the uterus. Most of the time, the egg breaks apart before it gets to the uterus. But that doesn't always happen. If a sperm from a boy's penis meets the egg on its way to the uterus, they can join together. The joining of an egg and a sperm is called fertilization.
Pregnancy begins if a fertilized egg attaches itself to the lining of the uterus.
When the egg breaks apart, the lining of tissue and blood isn't needed. It flows out of your uterus, through your cervix, through your vagina, and out of your body. This is called menstrual flow. You will be having your period when this happens to you. There are usually 14-16 days from ovulation to the beginning of a girl's period.