Predicting fetal lung maturity using the fetal main pulmonary artery Doppler indices

Abstract

Background: Non-invasive assessment of fetal main pulmonary artery (MPA) Doppler indices may provide a reliable predictor of neonatal respiratory distress syndrome (RDS). Aims and Objectives: This study aimed to evaluate the MPA Doppler indices as predictors of neonatal RDS and to correlate them with maternal and gestational factors. Materials and Methods: A prospective observational study was conducted on 100 singleton pregnancies between 28 and 37 weeks of gestation that was delivered within 72 h of Doppler assessment. MPA Doppler waveforms were recorded using standard ultrasonography protocols. Neonatal RDS was diagnosed based on clinical signs, radiographic findings, and responses to surfactant therapy. Receiver operating characteristic (ROC) analysis determined cutoff values, sensitivity, and specificity, while logistic regression identified independent predictors of RDS. Results: Among the 100 neonates, 24 developed RDS. Pulsatility indice (PI) was significantly lower (1.48±0.33 vs. 1.66±0.36, P=0.037), acceleration time (AT) shorter (59.33±7.52 vs. 66.89±7.06 ms, P<0.001), ejection time (ET) longer (227.25±25.72 vs. 204.79±19.62 ms, P<0.001), and AT/ET ratio reduced (0.258±0.036 vs. 0.325±0.035, P<0.001) in the RDS group. ROC analysis showed gestational age ≤236 days (sensitivity 83.33%, specificity 93.42%) and AT/ET ratio ≤0.29 (sensitivity 87.5%, specificity 88.16%) as the strongest predictors. Maternal age >26 years, PI ≤1.7, AT ≤56 ms, and ET >210 ms had moderate predictive values. Logistic regression confirmed AT/ET ratio and gestational age as independent predictors of RDS (area under the curve 0.908 and 0.921, respectively). No significant correlation was found between gestational age and AT/ET ratio (P=0.32). Conclusion: Fetal MPA Doppler assessment, particularly the AT/ET ratio combined with gestational age, is a reliable, non-invasive predictor of neonatal RDS. Multicenter studies are needed to validate the cutoff values and long-term outcomes.