If the second stage of labor is long, the fetal heart rate is low, and there are signs of hypoxia during labor, timely lateral incision is needed to avoid neonatal asphyxia. Physiological factors: 1. Poor perineal elasticity: If the perineum has good elasticity and moderate length, natural delivery is feasible without lateral incision. If the perineal elasticity is poor and the perineal body is short, continuous delivery is likely to lead to tearing or may cause damage to the anal mucosa and sphincter, and lateral incision is considered; 2, the size of the fetus: if the fetus is small and conducive to delivery, there is generally no need for lateral incision, if the fetus is large, there are difficulties in delivery, resulting in prolonged labor and the risk of fetal asphyxia, lateral incision is needed; 3, the number of deliveries: the cervical opening is looser for pregnant women, and delivery is faster without emergency. If the birth is quicker, no emergency can be taken without lateral incision. Second, delivery factors 1, the second labor is long: about 1-2 hours for primiparous women, more than 2 hours for the second labor is prolonged, common reasons are contraction weakness, narrow birth canal, too large fetus, abnormal fetal position, the need for timely lateral incision, less delivery time, to avoid damage to the mother and fetus, such as postpartum infection, uterine rupture, postpartum hemorrhage, neonatal asphyxia, cerebral palsy, etc.; 2, abnormal fetal heart: if the ultrasound shows that there umbilical cord around the neck and other conditions, when contractions, fetal heart drops, contractions stop, slow recovery of fetal heart, indicating that the fetus has a lack of oxygen performance, the need for timely lateral incision, to avoid fetal asphyxia. Therefore, whether or not to perform a lateral incision for childbirth depends mainly on the clinical situation and should be analyzed and judged according to the clinical situation.