The effect of intercourse on the fetus during pregnancy needs to be evaluated according to the pregnancy cycle, fetal development and the condition of the pregnant woman. Generally speaking, it is appropriate to have intercourse in the middle of pregnancy, but it is not recommended in the early and late stages of pregnancy.1. Early pregnancy: before 12 weeks of pregnancy, it is a critical period for the fertilized egg to be laid and the embryo to develop, at this time the fetus will be basically developed and shaped, the state is not stable, if intercourse is easy to cause miscarriage. And most pregnant women nausea, vomiting and other early pregnancy reactions are obvious, lower libido, weakened sexual response, no matter which aspect to consider is not suitable for intercourse; 2, mid-pregnancy: refers to 13-28 weeks of pregnancy, the fetus development is basically formed, more stable in the uterine cavity, pregnant women early pregnancy reaction weakened or disappeared, the body sex hormone level increased, sexual response sensitive. If the pregnant woman does not have abdominal pain, brown discharge and other uncomfortable conditions, pay attention to the position, frequency and strength of intercourse, it is possible to have intercourse and generally will not affect the fetus. But if the action is too aggressive, stimulating the uterus contraction, there will also be a risk of pre-eclampsia, premature rupture of membranes, etc.; 3, late pregnancy: refers to the 28 weeks of pregnancy to labor, because the development of the fetus in the uterine cavity volume increases, the pregnant woman’s abdomen expanded larger, fetal movement is obvious, the body gradually bulky, waist weight is also increasing, and is not suitable for intercourse. This time intercourse is more likely to cause contractions, which may cause premature rupture of the fetal membranes and premature delivery of the fetus.