In obstetrics, the uterus after cesarean section is called scarred uterus. As we all know, the rate of cesarean section in China was high in the early years due to various reasons. In recent years, with the implementation of the two-child birth policy, pregnant mothers with keloid uterus caused by the previous high cesarean section rate are faced with two choices in late pregnancy: A. Vaginal trial of labor after cesarean section B. Repeat cesarean section Vaginal trial of labor with keloid uterus helps to minimize repeat cesarean section and the related maternal and infant complications if the mother is able to have a vaginal delivery. And failed vaginal trial of labor is associated with increased morbidity for both mom and perinatal baby compared to elective repeat cesarean. Let’s start with a set of data (data from the textbook Obstetrics and Gynecology, 9th edition, People’s Health Publishing House): The success rate of vaginal trial of labor after cesarean section is about 60% to 70%. The incidence of uterine rupture after cesarean section is 0.5% to 0.9%. See here, many pregnant mothers will have a bunch of questions arise, do not worry, listen to the author one by one to analyze. Question 1: Who are the suitable candidates for trial of vaginal delivery after cesarean section? Answer: Suitable candidates are pregnant mothers who have a history of 1 previous lower uterine segment cesarean section and have no contraindications to vaginal trial of labor. Mothers at high risk for uterine rupture (e.g., classic or T-shaped uterine incision, previous history of uterine rupture, etc.) and those with contraindications to vaginal delivery are not appropriate candidates. Question 2: What are the issues to be considered for risk assessment? 1. indications of previous cesarean section and surgical procedure 2. age of the mother at the time of delivery 3. pre-pregnancy body mass index of the mother, her weight gain during pregnancy, and the weight of the baby 4. actual gestational week at the time of delivery 5. interval between pregnancies 6. whether there is any comorbid pregnancy complication such as pre-eclampsia The reason for the cesarean section in the previous pregnancy and the surgical procedure is one of the most important factors! The reason for cesarean section in the previous pregnancy may be different for every pregnant mom. Some pregnant mothers have failed vaginal attempts at labor (acute hypoxia of the baby during labor, oversized baby weighing >4KG, cephalopelvic disproportion where the baby’s head is not in proportion to the mother’s pelvis, etc.). Some pregnant mothers terminate their pregnancies by cesarean section directly before labor because of severe pregnancy complications or complications that do not allow for vaginal delivery. Others have cesarean sections simply because of social factors (fear of pain, choice of day, unwillingness to deliver vaginally, etc.). If these factors are no longer present in the second pregnancy, a trial of vaginal delivery may be considered. The type of uterine incision in an expectant mother with a scarred uterus can mostly be deduced from previous cesarean indications, but whether the procedure went well and there was no prolongation of the incision needs to be known by reviewing the operative record. In order for the physician to make a better decision about whether the mother is in a position to have a vaginal trial of labor, it is recommended that the surgical record related to the previous pregnancy’s cesarean section be provided. In general, a history of uterine rupture, a history of classical cesarean section with high longitudinal uterine incision, a history of >2 cesarean sections, an inverted “T” or “J” shaped incision in the lower uterine segment, extensive fundal uterine surgery, and a longitudinal uterine incision in the lower uterine segment are contraindications to vaginal delivery. Other associated factors: Older age of the mother (>35 years at the time of delivery), high pre-pregnancy body mass index (BMI >24 is considered overweight), large gestational weeks at the time of delivery (>40 weeks), high fetal weight (>4000 g), shorter inter-pregnancy intervals (<19 months), and preeclampsia are all factors that decrease the success rate of vaginal deliveries for keloid uterus mothers. PS: Vaginal delivery is less likely for mothers with scarred uterus who undergo induction or enhanced contractions than for those who undergo spontaneous labor (and very few hospitals in China are willing to induce labor for mothers with scarred uterus). After weighing the potential risks and benefits, the interest of each pregnant mother with a scarred uterus in a trial of vaginal labor varies widely. Many of the factors associated with the likelihood of success or uterine rupture in a vaginal trial of labor for pregnant mothers with a scarred uterus can be determined early in pregnancy. Therefore, for pregnant mothers with a high interest in a vaginal trial of labor, this issue should be emphasized at the start of prenatal care, and in order to improve the success rate of vaginal delivery, a sensible diet, appropriate exercise, normal weight gain, regular labor and delivery testing, and active prevention and treatment of pregnancy comorbidities and complications should be achieved during pregnancy. One last thing to talk about: not all obstetrics departments in hospitals offer vaginal trial of labor for pregnancies with scarred uterus, so it is important for expectant mothers to find out which medical institutions are qualified during pregnancy checkups. In short, whether it is a vaginal delivery or another cesarean section, the health and safety of both mom and baby are the most important thing. Therefore, whether or not the above conditions are met does not determine everything, each pregnant mother's situation is different, please refer to the advice of the attending doctor!