Doppler evaluation of the fetal pulmonary artery pressure

Background: The Doppler effect has allowed the characterization of several vessels in maternal-fetal circulation that have been used for practical purposes. Our review of the literature showed a paucity of information about fetal pulmonary artery pressure (FMPAP) and its behavior in regard to gestational age (GA). The objectives of the study were to evaluate a formula to calculate the main FMPAP and its correlation with GA. Methods: A total of 337 fetuses without obvious pathology were studied prospectively using Doppler evaluation of the FMPAP. Using the fetal main pulmonary artery Doppler acceleration time (FMPAT), we obtained the FMPAP using the following formula: FMPAP= 90 - (0.62 x FMPAT). Regression analyses, Pearson's bivariate correlation and paired sample t-test were used when appropriate. Results: FMPAT increases while FMPAP decreases with GA. Pearson's correlation coefficient for FMPAP and GA was -0.544 (P-value <0.001) and for FMPAT and GA was 0.556 (P-value <0.001). FMPAP and FMPAT were highly correlated (R = -0.972; P < 0.001). Conclusion: Pulmonary artery pressure in the fetus decreases with GA.