Objective: The aim of this study was to determine the factors predicting the probability of severe postpartum hemorrhage in women undergoing repeat cesarean delivery. Design: This multicenter, retrospective cohort study based on data from 11 public tertiary hospitals within 7 provinces of China. Setting: 11 public tertiary hospitals within 7 provinces of China. Population: 11074 eligible pregnant women who had a history of cesarean delivery and undergo cesarean delivery again after 28 weeks of gestation. Methods: The cohort was divided into the development and validation sets. The all-variables model and the multivariable logistic regression model (simple model) were fitted to estimate the probability of severe postpartum hemorrhage. Results: Six independent risk factors of severe postpartum hemorrhage in the simple model were selected from 40 clinical information features including a history of endometrial injury, complications with placenta previa or placenta accreta, lower gestational age at delivery, pelvic adhesion, and previous uterine incision status. Our final simple model showed excellent discrimination and calibration, with areas under the ROC curve of more than 0.90 in the validation set. Conclusions: Predictive tools based on patient clinical characteristics can be used to accurately estimate the probability of severe postpartum hemorrhage in patients undergoing repeat cesarean delivery. Funding National Key R&D Program of China (No. 2016YFC1000405 and 2017YFC1001402) and the National Natural Science Foundation (No. 81830045, 81671533 and 81571518). Keywords repeat cesarean deliveries; severe postpartum hemorrhage; placenta previa; placenta accrete; pelvic adhesion; prediction; obstetrics

Objective: To assess the indications and complications of late amniocentesis, as well as the advantagement of advanced genetic test results. Design: Retrospective analysis of case notes of women who underwent late amniocentesis. Setting: A tertiary fetal medicine center in China Population or Sample: 1243 pregnant women (1272 fetuses) that underwent amniocentesis at 24+0 to 39+4 weeks, between January 2014 and June 2019 in our hospital. Methods: Indications, complications, genetic test results and pregnancy outcomes were reported for each pregnancy. Information was obtained from case records, validated by research staff and analyzed by SPSS 21. Main Outcome Measures: Indications, complications, genetic test results, and pregnancy outcomes. Results: Of the 1243 women included, late detected abnormal ultrasound finding(s) (88.3%) comes to be the most common indication. PTB rate and IUD rates were 3.1% and 1.7% separately. Sixty-six fetuses with aneuploidy (5.2%) and Sixty-seven others with a pathogenic CNVs (5.3%) were identified by CMA. One pathogenic CNV (8.3%) were reported via WES. The diagnostic yield turned to maximal (31%) in the sub-group of fetuses with suspected prenatal diagnosis results, following by combination of ultrasound findings (23.1%). Conclusions: Since CMA and ES have considerable detection rates, it is reasonable to serve late amniocentesis as an effective and safe method to detect fetal abnormalities or reassure parents following late detected abnormal ultrasound findings. However, A percentage of CMA and ES may expose uncertain results like VOUS. Therefore, comprehensive genetic counseling is necessary. Key words: Prenatal diagnosis; Chromosomal-microarray-analysis; Fetal malformations; Late amniocentesis; Exon sequencing; Third trimester