 115 patients were enrolled in this study.Population was recruited from singleton pregnancies beyond 27 weeks of gestation.All participants underwent a ultrasound examination to measure fetal pulmonary artery acceleration to ejection time ratio PATET by a single experienced clinician. After the delivery respiratory distress diagnosis made by a pediatrician who were blinded the doppler waveform measurements.Following the diagnosis, neonates divided into 2 groups as RDS and RDS -. In addition of RDS diagnosis, neonatal features like 1st and 5th minute APGAR scores, neonatal intensive care unit NICU admission and duration in NICU were also recorded. Afterwards all parameters were statistically analyzed if there is any significant differences between those two groups. 