The five-month stomach hardness and tightness may be caused by physiological phenomena, pre-miscarriage and other reasons. 1. Physiological phenomenon: after pregnancy with the increase of gestational weeks, the enlarged uterus sensitivity will also increase, there may be occasional painless uterine contractions, not accompanied by shortening of the cervical canal, manifested in the stomach hard and tight, is a normal physiological phenomenon, does not require special treatment, and can be relieved after rest. 2. Pre-eclampsia: paroxysmal lower abdominal pain, manifested by hardness and tightness of the stomach, accompanied by a small amount of vaginal bleeding, combined with the history, clinical manifestations, ultrasonography can assist in the diagnosis. It is necessary to pay attention to appropriate rest, and give drugs to suppress contractions to protect the fetus. If you have a hard and tight stomach at five months, you can go to the hospital to find out the cause of the problem and deal with it positively.