A hard belly in the fourth month of pregnancy may be caused by several reasons: it may be related to the position of the fetus in the uterine cavity, it may be the occurrence of false contractions, or it may be a precursor to miscarriage. First, the position of the fetus in the woman’s uterus can affect the softness of her abdomen, and if the back or buttocks of the fetus is facing the woman’s belly, the belly may become hard. Second, false contractions may cause a hard belly when pregnant. The woman is 4 months pregnant already belongs to the middle of pregnancy, the middle of pregnancy, if the situation such as strain, may induce temporary pseudo contractions, this time the contractions and late pregnancy when the contractions of the fast delivery is different, the contractions at this time most of the external triggers, such as strain, excitement, etc., after the occurrence of contractions women should immediately rest, calm emotions, to avoid adverse consequences. Thirdly, the hardness of the belly caused by pre-miscarriage. The contractions are not conducive to the development of the fetus in the uterus, and persistent contractions may cause preterm abortion, but they are also accompanied by abdominal pain and vaginal bleeding.