Usually 36 weeks fetus refers to 36 weeks of pregnancy, 36 weeks of pregnancy belly tightness is mostly due to contractions, preterm labor, chest tightness belongs to the normal physiological phenomenon. Uterine contraction refers to the uterine smooth muscle contraction, in the contraction comes, pregnant women usually feel tightness in the lower abdomen, local tension becomes larger, lower abdomen hard and other symptoms. As the contractions become more frequent, pain, lower abdominal cramps and lumbago will occur. There is a relationship between the regularity of contractions and entering labor. The onset of preterm labor may be related to infection, bleeding from the meconium, and over distension of the uterus. There are often irregular contractions accompanied by a feeling of tightness in the abdomen. There may also be a feeling of the fetus descending, as well as a small amount of vaginal bleeding or bloody discharge. Chest tightness is a normal phenomenon that occurs mainly due to the increasing development of the fetus and the enlargement of the uterus, which squeezes the intestines, liver and lungs of the pregnant woman. In addition, pregnant women are advised to go to the hospital for relevant examinations in time and follow the doctor’s instructions for treatment.