A model to predict delivery time by induction of labour at term with a dinoprostone vaginal insert：A retrospective study

Abstract

Abstract Background: Dinoprostone vaginal insert is the most common pharmacological method of induction of labour for pregnant women. Few studies have predicted the vaginal delivery time (DT), our study aimed to analyse the primary factors for DT among women at or beyond term who underwent labour induction with dinoprostone vaginal inserts in the middle of China. Methods: In this retrospective observational study performed in the obstetric ward in Zhongnan Hospital of Wuhan University, we ultimately included all women at37 weeks 0 days to 41 weeks 6 days of gestation who underwent labour induction with vaginal dinoprostone between January 1st, 2019, and December 31st, 2021. The primary outcome was vaginal or caesarean delivery; the principal secondary outcome was influence for DT including several maternal complications and neonatal characteristics. Results: A total of 1,562 women at or beyond term underwent labour induction, and 71% (1109/1562) delivered vaginally. The median delivery time (DT) was 740.50 min, with an interquartile range from 443.25 to 1264.50 min. A total of 29% (453/1562) of the women gave birth by caesarean section, and 11.9% (54/453) were multiparous. Multiple linear regression analysis showed that multiparity, advanced maternal age, foetal macrosomia, premature rupture of membranes (PROM), and having dinoprostone inserted during the day all significantly influenced DT. A mathematical model was developed to integrate these factors for predicting DT: Y=804.478–125.284 × multiparity + 765.637 × advanced maternal age + 411.511 × foetalmacrosomia-593.358 × dinoprostone inserted during the day - 125.284×PROM. Conclusions: The DT with dinoprostone vaginal inserts was increased in women with advanced maternal age and foetal macrosomia, but decreased in multiparity, PROM, and dinoprostone inserted during the day.This study allows obstetricians to calculate a preliminary DT for pregnant women before placing a dinoprostone insert, which may be helpful to improve the management of patients and reduce the risk in busy maternity wards.