The Way of Human Reproduction Human reproduction is a natural life phenomenon. In terms of reproduction, commonly used methods in humans include sexual intercourse, artificial insemination, and in vitro fertilization. Among them, sexual intercourse is the most common natural method of childbirth and the most common method of pregnancy. During sexual intercourse, male sperm enters the female reproductive organ through the vagina, combines with the egg to form a fertilized egg, and eventually embeds into the uterine wall to form a fetus. Methods such as artificial insemination and in vitro fertilization are reproductive technologies used in some special circumstances that can help those who are unable to function normally