You can have sex after the third month of pregnancy because the placenta has formed and the pregnancy is relatively stable, so you can have sex, but you should pay attention to the frequency of sex not too frequent. If you have frequent sex, it may stimulate the contraction of the uterus, which will lead to temporary lack of oxygen to the fetus in the uterus, and if there is frequent temporary lack of oxygen, it may affect the growth and development of the embryo, and may even cause the embryo to stop developing. The frequency of sexual intercourse should be controlled appropriately, and attention should also be paid to the process of sexual intercourse not to be too rough, which will stimulate the contraction of the smooth muscle of the uterus, which will also lead to the possibility of pre-miscarriage or inevitable miscarriage, during pregnancy after the middle of pregnancy can have sex, but the above points should be noted.