A hard and tight stomach in the 5th month of pregnancy is more likely to be associated with physiological uterine contractions. Physiological contractions are called pseudo-uterine contractions or ineffective contractions, which usually appear after 12-14 weeks of pregnancy and are characterized by a feeling of tightness in the lower abdomen, which lasts for a short time, is not regular, is not accompanied by pain, does not have vaginal bleeding, shortening of the cervical canal and dilatation of the cervical opening, can appear after activity and will disappear after rest, or can appear at night and disappear early in the morning, and usually will not cause labor. Pregnant women do not need to be overly nervous, and proper rest is sufficient. However, if the hardness and tightness of the stomach lasts for a long time and is accompanied by vaginal bleeding, pathological contractions may have occurred. Pathological uterine contractions are seen in miscarriage or preterm labor. It is recommended to seek medical attention in time to identify the cause and carry out treatment so as not to cause miscarriage or preterm labor, which may affect the health of the fetus and the pregnant woman. In the 5th month of pregnancy, pregnant women should pay attention to keep warm, especially the abdomen, take rest, avoid overwork, have balanced nutrition, maintain personal hygiene, ensure sufficient sleep, and have regular prenatal checkups.