Intercourse in the first and second trimesters of pregnancy may result in the following clinical outcomes: 1. Pre-eclampsia may occur. As the stimulation during coitus causes uterine contraction, it will lead to the peeling off between the gestational sac and the uterine wall, so there will be vaginal bleeding, lower abdominal pain and so on. Clinical must bed rest, give timely arrangement of treatment. 2, may cause infection. Because of the lack of attention to sexual hygiene, pathogenic bacteria into the vagina and cause vaginal inflammation or cervical inflammation, or even the uterine cavity caused by the possibility of infection. 3, if the late pregnancy when the same sex, may lead to premature rupture of fetal membranes, clinically cause the possibility of preterm labor. Therefore, it is recommended not to have sex in the first and second trimesters of pregnancy.