Analysis of adverse pregnancy outcomes among pregnant women in Hunan Province from 2015 to 2023: Incidence, temporal trends, and risk factors.

OBJECTIVES: In recent years, China has witnessed marked changes in the fertility environment and the composition of women of childbearing age, making the prevention and control of adverse pregnancy outcomes (APOs) a major challenge for maternal and infant health management. This study aims to investigate the incidence, trends, and risk factors for APOs in Hunan Province from 2015 to 2023. METHODS: This was a retrospective cohort study of 5 279 639 pregnancies in Hunan Province hospitals from January 2015 to December 2023 using a province-wide web-based maternal health registry. The APOs included preterm birth (subclassified by gestational age), late-term birth, and term low birth weight (LBW). Multivariable Logistic regression and interrupted time series analysis (ITSA) were used to assess associations and policy impacts. RESULTS: The incidence of APO increased from 7.18% (2015) to 9.01% (2023), with the prevalence of extreme preterm birth increasing by 95.71%. The highest risk was associated with multifetal pregnancy (adjusted OR=21.13, 95% CI 20.88 to 21.38; singleton pregnancy as the reference). Advanced maternal age (40-44 years: OR=1.96, 95% CI 1.92 to 2.00; maternal age 25-29 years as the reference) and caesarean delivery (OR=1.36, 95% CI 1.35 to 1.37) were significant predictors. ITSA revealed an accelerated increase in APO incidence following the policy implementation (β=0.003, P<0.001). CONCLUSIONS: Demographic changes, including the increasing proportion of women of advanced maternal age, have contributed to the continuing rise in APOs. Targeted preventive interventions during pregnancy are urgently needed. These findings may provide evidence for the development of maternal health management policies in China and may also be applicable to comparable middle-income countries and regions.