What factors are needed to achieve a spontaneous pregnancy?

There are 4 basic events that must happen for a woman to become pregnant with natural conception. The first event is that the woman must release an egg from one of her ovaries, a process called ovulation. Second, a sperm must reach the egg and fertilize it to achieve conception. Third, the fertilized egg begins developing and must pass through the fallopian tube and be released into the uterus. Last, the fertilized egg must implant into the wall of the uterus, called the endometrium, in a process called implantation. If any of these four events are altered in any way, pregnancy either will not happen or result in a miscarriage.