The first three months of pregnancy are not allowed to have intercourse. The early stage of pregnancy is the key stage of embryo formation and development, early placenta and uterine wall connection is not very close, this period of time the uterus is more sensitive, the uterine shock caused by sex and orgasm triggered by the uterine contraction, the embryo has great harm, easy to cause miscarriage. Sex is also prone to bring in germs that can cause infections in the uterine cavity, thus jeopardizing the healthy development of the fetus. The contractions triggered by excessive excitement can also lead to changes in hormone levels in the body, which directly affects the stability of the fetus. Therefore, the early stages of pregnancy must try to avoid strenuous exercise, even if the fetus is stabilized in the middle of pregnancy, but also pay attention to the ways and means of coitus, try to avoid the uterus by the outside world stimulation led to premature birth, or premature rupture of membranes.