Aims: To correlate maternal-fetal Doppler velocimetry parameters to indices of fetal lung maturity (FLM).
Methods: Fifty-five consecutive third trimester pregnancies in which a pulsed-wave Doppler study, including uterine resistance index (Ut RI), umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI) and the UA/MCA ratio was performed within 24 hours before amniocentesis and within a week from birth. FLM was determined by amniotic fluid lamellar bodies count (LBs).
Results: A positive correlation between MCA PI and LBs (p < 0.007, r = 0.44) was found. MCA PI showed a trend to lower values in fetuses that developed RDS at birth (1.3 +/- 0.5 vs. 1.7 +/- 0.4, NS). LBs significantly decreased as Ut RI increased (O.R.: 0.98, C.I. 0.97-0.99, p < 0.05). A mean Ut RI > 0.64 was correlated to delayed FLM (LBs < 20,000/microl; sensitivity: 90.9%, specificity: 90.3%; positive predictive value: 76.9%, negative predictive value: 96.6%).
Comment: In third trimester pregnancies abnormal uterine artery waveforms may be associated to a delayed FLM, as expressed by decreased amniotic fluid LBs.