Correlation of Doppler Pulmonary Artery Parameters With Gestational Age in Normal Fetuses at 20-32 Weeks.

Objective: To measure pulmonary artery (PA) diameters and Doppler values in normal fetuses and to analyze their trends and correlations with gestational age (GA).

Methods: We took PA ultrasound measurements of normal fetuses with GAs of 20-32 weeks, including the main pulmonary artery (MPA), right pulmonary artery (RPA), and left pulmonary artery (LPA) inner diameters and MPA Doppler parameters [acceleration time (AT), ejection time (ET), AT/ET ratio, peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI)]. The subjects were divided into early (20-24 weeks), middle (24-28 weeks), and late (28-32 weeks) GA groups.

Results: In total, 336 fetuses with GAs of 21 + 3 weeks to 31 + 2 weeks were included (early, n = 161; middle, n = 105; late, n = 70). The PSV, EDV, AT, ET, and PA diameters correlated positively with the GA. The correlations of the PA diameters were the strongest, and a linear regression model was obtained: MPA diameter (cm) = (-0.286 + 0.005) × GA (days).

Conclusions: The MPA, PI, RI, and AT/ET ratios are relatively stable before the GA of 32 weeks. The MPA, LPA, and RPA diameters increase with the GA.