Neonatal and maternal adverse outcomes among low-risk nulliparous women compared with multiparous women at 37-41 weeks of gestation: a cohort study in South China.

Objective: The objective of this study was to compare the differences in neonatal and maternal adverse outcomes between low-risk full-term nulliparous (women giving birth for the first time) and low-risk full-term multiparous (women who have given birth previously) using a database from 18 hospitals. Methods: The cohort study, conducting from January 2019 to December 2019, described the frequency of maternal and neonatal adverse outcomes in low-risk nulliparous women and multiparous women who labored at 37-41 weeks of gestation. The association between maternal parity and the risk of neonatal and maternal adverse outcomes were analyzed based on multivariate Poisson regression. Results: Of the 75,033 live births during the study period, 49,935 (66.55%) met the inclusion criteria, including 44.18% of nulliparous women and 55.82% of multiparous women. After adjustment, the risk of maternal adverse outcomes was 0.56 times reduced in multiparous women compared to nulliparous women (aRR 0.56, 95% CI 0.52-0.65, 44% lower risk), and the incidence of complication interventions in multipara was lower than in nullipara (aRR 0.76, 95% CI 0.59-0.99). Macrosomia and low birth weight were the most common neonatal adverse outcomes in the two groups. There was no statistically significant difference in neonatal adverse outcomes between multipara and nullipara after controlling for confounders. Conclusion: Among low-risk women who delivered at 37-41 weeks of gestation, the risk of maternal adverse outcomes and the incidence of complication interventions in nulliparous women were higher than in multiparous women. There was no statistically significant difference in adverse neonatal outcomes between two groups after adjustment.