Sexual intercourse is not allowed in the first and second trimesters of pregnancy. In the first trimester, due to the instability of the embryo, if you have sex, sexual excitement will cause the uterus to contract, causing the peeling off between the gestational sac and the uterine wall, and there will be the possibility of preterm miscarriage or inevitable miscarriage. Therefore, you cannot have intercourse in the first trimester of pregnancy. In the second trimester of pregnancy, if you have intercourse there is a possibility of preterm labor, premature rupture of membranes, or the possibility of infection in the clinic. Therefore, coitus is also not allowed in the second trimester of pregnancy. In the middle of pregnancy, you can have normal sex, but it is recommended that the frequency of sex should not be too frequent. Because too frequent sex will stimulate the uterus to contract. Frequent uterine contractions will lead to intrauterine oxygen deprivation of the fetus, resulting in fetal developmental delay, and in serious cases, there may be the possibility of fetal death in the uterus.