Pulmonary Vascular Doppler and Fetal Lung Biometry as Predictors of Neonatal Respiratory Complications in Early- and Late-Onset Fetal Growth Restriction.

OBJECTIVE: To determine the prognostic value of third trimester main pulmonary artery (MPA) Doppler indices, two dimensional (2D) lung volume, and thoracic circumference (TC) for composite adverse pulmonary outcome (CAPO) in pregnancies complicated by fetal growth restriction (FGR).

METHODS: In this prospective cohort, 105 singleton FGR pregnancies (28 + 0 - 37 + 0 weeks) and 108 controls underwent standardized ultrasound at a tertiary center. MPA acceleration time (AT), ejection time (ET), and pulmonary AT to ET (PAT/ET) ratio were recorded. 2D lung volume and TC were calculated from axial thoracic sections. The CAPO comprised ≥ 1 of: 5-min Apgar < 7, respiratory distress syndrome (RDS), continuous positive airway pressure (CPAP), mechanical ventilation, or neonatal intensive care unit (NICU) admission for respiratory compromise.

RESULTS: Compared with controls, FGR fetuses had smaller lung volume and TC, higher MPA pulsatility/resistance indices, and lower PAT/ET. CAPO occurred in 42.9% of FGR versus 10.2% of controls. Optimal cut-offs were AT < 50.5 ms, PAT/ET < 0.19, and lung volume < 18.9 mL. In multivariable analysis, PAT/ET < 0.19, AT < 50.5 ms, lung volume < 18.9 mL and preterm delivery independently predicted CAPO. Combining PAT/ET and lung volume increased sensitivity to 82% with 72% specificity.

CONCLUSIONS: Reduced lung volume and aberrant MPA Doppler profiles identify growth restricted fetuses at heightened risk of early neonatal respiratory morbidity. Integrating these pulmonary markers into FGR surveillance may enhance antenatal risk assessment, optimize steroid and delivery timing, and improve neonatal respiratory outcomes.