Ovulation is the process of releasing a mature egg from the ovaries. It occurs each month in women of reproductive age about two weeks after the first day of menstruation. The egg then moves into the fallopian tube.
40 - 150 million sperm can be released from a male in one ejaculation. These sperm move towards the egg and can live for 48 - 72 hours.
Fertilization occurs when the sperm penetrates the egg.
The fertilized egg quickly starts dividing into many cells and enters the uterus 3 - 4 days after fertilization.
Implantation occurs when the egg attaches to the lining of the uterus, called the endometrium. A hormone called human chorionic gonadotropin (hCG) is produced from cells that will form the placenta and can be detected in the mother's blood or urine within 1 - 2 weeks.