Adult men and women who have normal sexual intercourse, with normal ovulation and normal sperm, may become pregnant. The sperm and egg combine to form a fertilized egg, which under the peristaltic movement of the fallopian tube enters the uterine cavity and lays, grows, develops, and forms an embryo, which slowly grows to form a fetus. Then after 37 weeks of pregnancy is full term, through vaginal delivery or through cesarean section, this is where the child comes from. The main thing is to have a normal egg and normal sperm, and the fallopian tubes are open, and to have a normal sex life, in order to achieve pregnancy.