Intercourse is not recommended for three months after ovulation and conception as it may cause uterine contractions and increase the risk of miscarriage. A woman’s fetus is not fully stabilized in the first trimester of pregnancy, so if you have intercourse in the first trimester, it may stimulate the uterus causing contractions and increasing the risk of miscarriage. Moreover, the first trimester is a critical period for the development of the embryo, so if you don’t pay attention to hygiene when having intercourse, resulting in infection, the normal development of the embryo may be affected. In the second trimester, coitus should also be avoided as much as possible, because coitus may stimulate the uterus, leading to premature rupture of fetal membranes and triggering preterm labor. And if a bacterial infection occurs during coitus in the second trimester, the bacteria may enter the uterus and increase the risk of puerperal infection.