A hard tummy at 18 weeks after pregnancy may lead to preterm miscarriage. First of all, we should reduce the amount of activity and rest in bed to avoid aggravating the symptoms of hard tummy because of high activity. As the weeks of pregnancy increase, especially after the third month of pregnancy, the uterus gradually overflows out of the pelvis into the abdominal cavity. The sensitivity of the uterus increases during this period, coupled with the hormonal changes in the body and the increasing size of the fetus, and fetal movement may occur at 18 weeks, all of which tend to stimulate the uterus to contractions and the symptoms of a hard stomach, which are generally relieved by physiological bed rest. If it does not ease, the occurrence of pre-eclampsia cannot be completely excluded. It is recommended to go to the hospital immediately for a clear diagnosis and symptomatic treatment to avoid miscarriage. It is recommended that pregnant women in mid-pregnancy be moderately active, eat a reasonable diet and have balanced nutrition, which is beneficial to the health of the pregnant woman and the growth and development of the fetus.