Value of Multimodal Ultrasound in Assessing Fetal Lung Maturity in Hypertensive Disorders of Pregnancy

Objective To investigate the value of quantitative parameters derived from multimodal ultrasound in assessing fetal lung maturity (FLM) in pregnancies complicated by hypertensive disorders of pregnancy (HDP). Methods This prospective study enrolled 395 women with singleton pregnancies between 24 + 0 and 40 + 6 weeks of gestation, including 130 in the HDP case group and 265 in the normal pregnancy control group. All participants underwent multimodal ultrasound examination (including two-dimensional, three-dimensional, and spectral Doppler). Quantitative measurements were obtained for fetal pulmonary structural parameters (bilateral lung areas and lung volumes) and hemodynamic parameters. Hemodynamic parameters included the peak systolic velocity to end-diastolic velocity ratio (S/D), pulsatility index (PI), and resistance index (RI) of the umbilical artery (UA) and middle cerebral artery (MCA), as well as pulmonary artery acceleration time (AT), ejection time (ET), and the AT/ET ratio. In the case group, the occurrence of neonatal respiratory distress syndrome (NRDS) was recorded. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of NRDS, and a combined prediction model was constructed. The diagnostic performance of the model was evaluated using the receiver operating characteristic (ROC) curve. Results The incidence of NRDS in the HDP case group (31.54%) was significantly higher than that in the control group (7.92%) ( P  < 0.001). Fetuses in the case group exhibited smaller bilateral lung areas and volumes compared to the control group, with a trend of more pronounced pulmonary developmental delay as gestational age advanced. Regarding hemodynamics, the case group demonstrated a "brain-sparing effect" pattern, characterized by increased UA-PI and UA-RI alongside decreased MCA-PI and MCA-RI. Furthermore, pulmonary artery AT and the AT/ET ratio were significantly lower in the case group (all P  < 0.001). Multivariate analysis identified gestational age (OR = 0.68), HDP (OR = 17.26), pulmonary artery AT (OR = 0.94), UA-PI (OR = 8.33), and MCA-PI (OR = 0.19) as independent predictors of NRDS. The combined prediction model yielded an area under the curve (AUC) of 0.828 (95% CI: 0.798–0.902). Conclusion HDP can lead to fetal pulmonary developmental delay and characteristic hemodynamic alterations. The multimodal ultrasound-based combined prediction model, incorporating gestational age, HDP status, pulmonary artery AT, UA-PI, and MCA-PI, demonstrates excellent predictive ability for the risk of NRDS.