The fifteenth week of pregnancy belongs to the middle stage of pregnancy, you can have intercourse. Early pregnancy embryo and uterine wall combination is not stable, sex can induce miscarriage; late pregnancy, the fetus is larger, the pressure of the uterine cavity is larger, sex can induce premature rupture of membranes, placental abruption, uterine cavity infection and other risks, late pregnancy should not have sex. Mid-pregnancy embryo has formed a fetus, the uterine pressure is not big, the fetus and pregnant women are relatively stable, sex has little effect on the fetus and pregnant women, you can have sex. Mid-pregnancy intercourse should not be too frequent, sex action should not be rough, in order to pregnant women do not feel uncomfortable is appropriate. If there is placenta praevia repeated vaginal bleeding, cervical insufficiency, a history of habitual abortion, sex is likely to lead to maternal bleeding, abortion, infection, etc., pregnancy should not have sex. In mid-pregnancy coitus abnormalities need to be stopped immediately, timely consultation, under the guidance of the doctor to identify the causes and give treatment.