Since the implementation of the "universal two-child" policy, multiparous women has become the main labor and delivery population. Problems such as advanced maternal age, chronic comorbidities, obstetric complications and pregnancy after cesarean section have become increasingly prominent, bringing new challenges to obstetricians.

To analyze the current status of cesarean section in multiparous women under the new childbearing policy based on the revised Robson classification system, in order to provide data support for rational control of cesarean section rate, improvement of obstetric care.

A total of 19 170 women who delivered by cesarean section in the Tenth Affiliated Hospital, Southern Medical University from 2017 to 2020 were included and divided into the primipara group (n=5 630) and multiparous group (n=13 540). Maternal information including age, gravity, parity, previous deliveries, fetal position, pregnancy comorbidities and complications, maternal and fetal outcomes, was collected through the electronic medical records. The general information and maternal and neonatal outcomes of the two groups were compared. The revised Robson classification system was used to classify the parturients according to their obstetric characteristics (parity, fetal position, number of fetuses and gestational weeks of delivery). The distribution of parturients in the revised Robson classification system and the change of the proportion of parturients in each group with year were compared.

The proportion of pregnancy after cesarean section was as high as 81.4% (11 026/13 540). The age, gravity, parity, proportion of age ≥35 years and gestational diabetes mellitus of the multiparous group were higher than the primipara group (P<0.05). Based on the revised Robson classification system, R3 class (singleton cephalic position at ≥37 weeks' gestation with a history of at least 1 cesarean delivery) accounted for the highest proportion (50.4%, 9 668/19 170) in all cesarean section, followed by R1 class (singleton cephalic primiparous labor at≥37 weeks' gestation, spontaneous labor, induced labor, or cesarean section before labor) (20.8%, 3 993/19 170). In multiparous women, R3 class accounted for 71.4% (9 668/13 540). Analysis of the population characteristics of multiparous women found that the proportion of R3 class, which had the highest proportion, decreased from 73.5% to 67.1%, while the proportion of R2 class [transplants with singleton cephalic position at ≥37 weeks' gestation (without history of cesarean section), spontaneous labor, induced labor, or cesarean section before labor], and R8 class [all singleton cephalic positions at <37 weeks' gestation (including history of cesarean section) ] all increased. The 24-h postpartum hemorrhage and the proportion of blood transfusions were higher in the multiparous group than the primipara group, while length of hospital stay after surgery was lower than that in the primipara group (P<0.05). A total of 20 026 newborns were delivered by 19 170 women, including 6 077 primipara women and 13 949 multiparous women; the birth weight and 1-minute Apgar score of neonates in the multiparous group were higher than the primipara group, while the proportions of 1-minute ≤7 and neonatal transfers were lower than those in the primipara group (P<0.05). There was no significant difference in 5-minute Apgar score between the two groups (P>0.05) .

Advanced age and pregnancy after cesarean section are prominent features of multiparous women. Although the proportion of R3 class decreased by year, it is still the main population of cesarean section. In order to reduce cesarean section rate, it is necessary to effectively control the cesarean section of primipara women, and actively promote the vaginal trial of labor for women in R3 class. Meanwhile, the proportion of R2 and R8 in the multiparous women, which put forward new requirements for clinical practice of obstetrics.

自"全面二孩"政策实施后，经产妇为主要分娩人群，高龄、慢性合并症、产科并发症、剖宫产术后再次妊娠等问题日渐突出，给产科工作者带来新的挑战。

基于修正版Robson分类系统对新生育政策下经产妇的剖宫产现状进行分析，为合理控制剖宫产率、提高产科医疗质量提供数据支持。

纳入2017—2020年在南方医科大学第十附属医院剖宫产分娩的产妇共19 170例，分为初产妇组（n=5 630）和经产妇组（n=13 540）。通过电子病历系统收集产妇信息，包括年龄、孕产次、既往分娩情况、胎方位、妊娠合并症及并发症、产妇结局及新生儿结局等，并对两组产妇的一般资料、产妇结局及新生儿结局进行比较。采用修正版Robson分类系统，根据产科特征（产次、胎位、胎儿数量、分娩孕周）对产妇进行分类，对比两组在修正版Robson分类系统中的分布及各组占比随年度变化情况。

经产妇中剖宫产后再次妊娠的比例高达81.4%（11 026/13 540）；经产妇组的年龄、孕次、产次及年龄≥35岁、妊娠合并糖尿病比例均高于初产妇组（P<0.05）。修正版Robson分类在所有剖宫产产妇中，以R3类（妊娠≥37周单胎头位，至少有1次剖宫产史）为主（50.4%，9 668/19 170），其次为R1类（妊娠≥37周单胎头位初产，自然临产、诱导临产或临产前剖宫产）（20.8%，3 993/19 170）；经产妇中，R3类的占比最高达71.4%（9 668/13 540）。分析经产妇人群特征发现，2017—2020年，占比最高的R3类产妇从73.5%下降至67.1%，而R2类[妊娠≥37周单胎头位经产（无剖宫产史），自然临产、诱导临产或临产前剖宫产]、R8类[所有妊娠<37周单胎头位（包括有剖宫产史）]的占比均有所升高。经产妇组产后24 h出血量、输血比例高于初产妇组，而术后住院天数低于初产妇组（P<0.05）。19 170例产妇共分娩新生儿20 026名例，其中初产妇分娩6 077例，经产妇分娩13 949例；经产妇组新生儿出生体质量、1 min Apgar评分高于初产妇组新生儿，而1 min Apgar评分≤7分、转新生儿科比例低于初产妇组新生儿（P<0.05）；两组产妇剖宫产新生儿5 min Apgar评分比较，差异无统计学意义（P>0.05）。

高龄和剖宫产术后再次妊娠是经产妇的突出特征。R3类的占比虽然逐年下降，但仍是剖宫产经产妇的主要人群，为降低剖宫产率，需有效控制初次分娩剖宫产，并在安全的前提下积极推广R3类产妇经阴道试产。同时，经产妇中R2类和R8类的占比有所升高，对产科临床实践提出了新的要求。