The first trimester of pregnancy when the embryo is not yet stable, if coitus may cause the following effects: First, on the development of the fetus itself will not lead to malformation, but may lead to miscarriage, because coitus will make the uterine smooth muscle contraction, which will lead to the gestational sac and the uterine wall between the peeling or the placenta and the uterine wall between the peeling, may lead to the possibility of preeclampsia or even miscarriage. Secondly, if there are contractions in the first trimester of pregnancy, it may lead to the possibility of miscarriage. Secondly, if you have intercourse during the first trimester of pregnancy and do not pay attention to sexual hygiene, it may lead to infection of the reproductive tract, and in serious cases, it may also lead to intrauterine infection, which poses a direct threat to the fetus, and may lead to the possibility of fetal death in the uterus. Therefore, it is recommended that coitus be prohibited during the first trimester of pregnancy, and this point should be given special attention.