The Effectiveness and Safety of the Trial of Labor in Full Term Pregnant Women With Cesarean Section After Spontaneous Labor

In the cesarean section group, the extra inclusion criteria includes: Only one prior low transverse uterine incision;Extra exclusion criteria:1. With mutiple history of c esction;2. Prior extensive transfundal uterine surgery, such as for fetal surgery, myomectomy, or uterine reconstruction; Prior classical vertical uterine incision, or an inverted "T" or "J" incision;3. Short interpregnancy interval;4.Prior uterine rupture or dehiscence, or cesarean scar pregnancy;4.Evaluated fetal birth weight> 4000 g.

In the non-cesarean section group, the extra criteria should include: nulliparous

Inclusion Criteria:

1. Volunteers sign the informed consent
2. Age: 20-40 years;
3. Singleton, a cephalic presentation;
4. No contradiction to vaginal delivery; 5.39~42 weeks; 6.Spontaneous labor

Exclusion criteria:

1. Konwn contraindication to vaginal delivery or severe complications;
2. Multiple gestation;
3. Uterine malformation;
4. Severe psychiatric disorder;
5. Without family's support.