Development and validation of a risk prediction model for preterm premature rupture of membranes: a cross-sectional study at North Wollo Zone governmental hospitals, Northern Ethiopia

Abstract

OBJECTIVES: To develop and validate a risk prediction model for preterm premature rupture of membranes (PPROM) to enable early identification of at-risk women and support clinical decision-making in North Wollo Zone, Ethiopia. DESIGN: A hospital-based retrospective cross-sectional study. SETTING: Six public hospitals in the North Wollo Zone, Northern Ethiopia. PARTICIPANTS: A total of 1098 pregnant women were included in the study using systematic random sampling. PRIMARY OUTCOME MEASURES: Occurrence of PPROM. METHODS: Data were collected between 20 November 2023 and 20 March 2024, using structured interviews and medical record reviews. A risk prediction model was developed using Least Absolute Shrinkage and Selection Operator and logistic regression. Model performance was assessed through area under the curve (AUC), calibration plots and the Hosmer-Lemeshow test. Internal validation was conducted via bootstrap resampling. A simplified risk score was created to categorise women into high-risk and low-risk groups, and its clinical utility was evaluated using decision curve analysis. RESULTS: Among the 1098 participants (100% response rate), the mean age was 21.54 years (IQR: 18-26), with 57.2% aged 20-34 years. The prevalence of PPROM was 10.75% (95% CI 9.01% to 12.77%). Seven significant predictors were identified: maternal age <20 years, urinary tract infection, anaemia, history of PROM, pregnancy-induced hypertension, short birth interval and polyhydramnios. The model demonstrated good discrimination (AUC=0.873; bias-corrected AUC=0.87). A simplified risk score (range 3-13) using a cut-off of ≥6.5 classified women into low-risk and high-risk groups, with PPROM incidence rates of 4.76% and 38.7%, respectively. Decision curve analysis showed good clinical utility, and a nomogram was developed for individualised risk assessment. CONCLUSIONS: PPROM remains a significant obstetric complication in the study area. The validated risk prediction model showed moderate to good performance and can be used to support early screening and risk-based management in antenatal care (ANC). Integrating the tool into routine ANC services, along with health education and management of modifiable risk factors, may help reduce PPROM-related adverse outcomes. Further external validation is recommended.