In the fourth month of pregnancy, the phenomenon of hardness and tightness of the belly, if there is no painful sensation, this means that there are pseudo contractions. This is because in the fourth month of pregnancy, the fetus will move and the process of fetal movement will stimulate the uterus, causing it to have convulsive contractions. This is a physiological phenomenon, which is more frequent at night and less frequent during the day than at night. However, if the hardness of the stomach is more frequent, it may be a sign of pre-miscarriage and should be seen by a doctor.