Background: Cesarean section (CS) is an independent risk factor for placenta accreta. Some researchers think that the timing of primary cesarean delivery is associated with placenta accreta in subsequent pregnancies. The aim of this study was to investigate the risk of placenta accreta following primary CS without labor, also called primary elective CS, in a pregnancy complicated with placenta previa.
Methods:: A retrospective, single-center, case-control study was conducted at Peking University Third Hospital. Relevant clinical data of singleton pregnancies between January 2010 and September 2017 were recorded. The case group included women with placenta accreta who had placenta previa and one previous CS. Control group included women with one previous CS that was complicated with placenta previa. Maternal age, body mass index, gestational age, fetal birth weight, gravity, parity, induced abortion, the rate of women received assisted reproductive technology, other uterine surgery, and primary elective CS were analyzed between the two groups.
Results:: The rate of primary elective CS (90.1% vs. 69.9%, P < 0.001) was higher, and maternal age was younger (32.7 ± 4.7 years vs. 34.6 ± 4.0 years, P < 0.001) in case group, compared with control group. Case group also had higher gravity and induced abortions compared with the control group (both P < 0.05). Primary CS without labor was associated with significantly increased risk of placenta accreta in a subsequent pregnancy complicated with placenta previa (odds ratio: 3.32; 95% confidential interval: 1.68-6.58).
Conclusion:: Women with a primary elective CS without labor have a higher chance of developing an accreta in a subsequent pregnancy that is complicated with placenta previa.
初次剖宫产时机与胎盘植入关系的研究摘要目的：剖宫产(CS)是胎盘植入的独立危险因素。有研究表明，在随后的妊娠中，初次剖宫产的时机与胎盘植入有关。本研究探讨了初次剖宫产时机与再次妊娠合并前置胎盘者发生胎盘植入的关系。 方法：本单中心病例对照回顾性研究选择了2010年1月至2017年9月在北京大学第三医院的单胎分娩数据。诊断为胎盘植入合并前置胎盘且只有一次剖宫产史者被纳入病例组，对照组则与病例组相匹配纳入了合并前置胎盘且只有一次剖宫产史者。比较两组间孕妇年龄、体重指数 (BMI)、分娩孕周、胎儿体重、孕次、产次、人工流产次数、接受辅助生殖技术 (ART) 的比率、其他子宫手术史的比率和既往选择性剖宫产的比率的差别。 结果：与对照组相比，病例组初次择期剖宫产率更高 (90.1% vs. 69.9%, P<0.001)、孕妇的年龄更低 (32.7±4.7 岁 vs. 34.6±4.0岁, P<0.001)。病例组孕次及流产次数则明显高于对照组 (均为P<0.05)。初次剖宫产手术为临产前者再次妊娠合并前置胎盘后发生胎盘植入的风险明显升高 (OR: 3.32; 95% CI: 1.68-6.58)。 结论：初次剖宫产手术为临产前的孕妇再次妊娠合并前置胎盘时，发生胎盘植入的风险明显升高。.
Keywords: Cesarean Section; Placenta Accreta; Placenta Previa.