The feeling of hard, tight, taut and swollen belly in the 6th month of pregnancy, if there is no pain, this is a physiological manifestation. In the process of pregnancy, the fetus grows, the uterus enlarges, especially in primiparous women, will show the phenomenon of a tighter, harder belly, in the process of fetal activity will also appear local lumpy phenomenon, these are normal performance. During this period, try to pay attention not to exercise strenuously, not to overwork, to avoid stimulating the uterus, triggering the phenomenon of uterine contractions aggravated. If frequent uterine contractions occur, it may lead to rapid fetal heart rate, increased fetal movements and, in severe cases, intrauterine ischemia and hypoxia. This may lead to fetal arrest or intrauterine asphyxia.