Objective To compare the frequency of Ureaplasma-positive gastric fluid (GF) cultures based on the cause and mode of delivery in preterm newborns. Design Retrospective cohort study. Setting A single university hospital in South Korea. Population Women with a singleton pregnancy who delivered prematurely (between 23+0 and 32+0 weeks of gestation, N=464). Methods The newborns’ GF was obtained on the day of birth via nasogastric intubation. The frequency of Ureaplasma-positive GF cultures was compared according to the cause and mode of delivery. Main outcome measures Ureaplasma spp.-positivity in GF cultures. Results Ureaplasma spp. was detected in 20.3% of the GF samples. The presence of Ureaplasma spp. was significantly higher in the spontaneous preterm birth group than in the indicated preterm birth group (30.2% vs 3.0%; P < 0.001). Additionally, Ureaplama spp. was more frequently found in the vaginal delivery group than in the cesarean delivery group, irrespective of the cause of preterm delivery [indicated preterm birth group (22.2% vs. 1.9%, P = 0.023); spontaneous preterm birth group (37.7% vs. 24.2%, P = 0.015)]. Conclusions Ureaplasma spp. were found in 20.3% of the GFs. However, only 1.9% of newborns in the indicated preterm birth group with cesarean delivery had a Ureaplasma-positive GF culture. Our findings support the view that the amniotic cavity is a sterile environment before the onset of parturition. Funding Ministry of Health & Welfare and Ministry of Science and ICT, Republic of Korea (Grant No. HI22C1859) and the Seoul National University Bundang Hospital Research Fund (Grant No. 14-2021-0025).

Objective: The purpose of this study was to develop a predictive model for cesarean delivery after induction of labor (IOL) in twin pregnancy. Design: Retrospective cohort study Setting: University hospital. Population: Twin pregnancy who underwent IOL from 2005 to 2018 Methods: The study population was randomly divided into the training and test sets at a ratio of 2:1. Three-fold cross-validation (CV) with 100 times repetitions was applied to select the best model. Main outcome measure to develop and validate a prediction model for cesarean delivery after IOL in twin pregnancies. Results: A total of 1,703 twin pregnancies were analyzed, including 1,356 women in the development cohort of the SNUH database and 347 women in the external validation cohort of the SNUBH database. In the development cohort, the clinical variables that were different between the successful and failed IOL groups were included in the logistic regression analysis, and the final prediction model, composed of five variables (maternal age, maternal height, parity, cervical effacement, and summated birth weight of both twins), was selected with an AUROC of 0.742 (95% confidence interval [CI], 0.700-0.785) and 0.733 (95% CI, 0.671-0.794) in the training set and test set, respectively. A nomogram for predicting the risk of cesarean delivery after IOL in twin pregnancies was also developed. Conclusion: A prediction model to provide information and evaluate the risk of cesarean delivery after IOL in twin pregnancies was developed. Keywords Twin pregnancy, induction of labor, cesarean section, prediction model