Objective: This study aimed to assess FLM before labour to minimize the incidence of neonatal RDS in cesarean section deliveries by measuring fetal pulmonary artery doppler indices. Methods: This observational cross sectional study was performed on 100 women undergoing cesarean sections from August 2017 till October 2020 at Obstetrics & Gynecology Department, Faculty of Medicine, Zagazig University. Detailed history, physical examination, detailed obstetric ultrasound examination were done. By using 2D voluson pro-730 ultrasound equipped with a 3 to 5 MHz convex array sector transducer with comment on placental location and maturity, fetal biometry (BBD, HC, FL, AC), estimated fetal weight and amniotic fluid index. fetal MPA waveform was obtained, relevant Doppler velocity variables were manually traced three times and the average was taken. The variables included the systolic/diastolic (S/D) ratio, pulsatility index (PI), resistance index (RI), PSV and the At/Et ratio. Neonates are assessed by a pediatrician to diagnose presence of respiratory distress. For statistical analysis, we used the Statistical Packages for Software Sciences (SPSS) version 21. Results: Mean age of patients was 28.28 years old, mean gestional age was 38.354 weeks. Mean amniotic fluid index was 7.37. mean neonatal birth weight was 3078 gram. Seventeen percent has developed RDS while, Fourteen percent was admitted to NICU. All patients had delivered by CS. Seventy-eight percent of them had elective CS. there is significant relation between development of RDS and gestational age at delivery. mean S/D ratio 6.866. mean PI 2.17 cm/S. mean RI 0.768 cm/S. mean PSV 68.255 cm/S. mean AT/ET ratio 0.312. There is statistically significant relation between RDS development and each of S/D ratio, PI, RI, and AT/ET ratio. (S/D ratio, PI and RI were significantly higher in neonates had RDS while those patients had significantly lower AT/ET ratio). There is statistically non-significant relation between RDS development and PSV. The best cutoff of AT/ET ratio in diagnosis of respiratory distress among our studied neonates was<0.283 with area under curve 0.868 with sensitivity 82.4%, specificity 97.6%, positive predictive value (PPV) 87.5%, negative predictive value (NPV) 96.4% and accuracy 95% (p<0.05) .The ability of S/D ratio, PI, RI and PSV to predict RDS development had the same sensitivity but lower specificity compared with that of At/Et . Conclusions: The Pulmonary artery AT/ET measurement may provide a noninvasive means of determining FLM with relatively acceptable levels of sensitivity, specificity, and predictive values.