Fetal Pulmonary Artery Acceleration/Ejection Ratio for Transient Tachypnea of the Newborn in Uncomplicated Term Small for Gestational Age Fetuses.

OBJECTIVE: Transient tachypnea of the newborn (TTN) is the leading cause of neonatal morbidity in preterm deliveries and has been reported in term small-for-gestational-age (SGA) fetuses; therefore, determination of fetal lung maturity before delivery is extremely important. Our present study aimed to evaluate the ratio of fetal pulmonary artery acceleration time to ejection time (At/Et) in uncomplicated term SGA fetuses and whether this ratio changes with TTN.

STUDY DESIGN: One hundred seventy-five pregnant women with uncomplicated pregnancies who delivered after 37 gestational weeks were included in this cross-sectional study. Participants were divided by birth weight percentiles into SGA (n = 86) and healthy control groups (n = 89). All participants underwent ultrasound examination to determine fetal pulmonary artery At/Et. After delivery, the neonates were grouped according to diagnosis of TTN (i.e., TTN-positive SGA group [n = 14], TTN-negative SGA group [n = 72], and TTN-negative control group [n = 86]), and the fetal pulmonary artery At/Et was compared between the two.

RESULTS: Maternal demographic characterizes were similar between groups. At/Et was 0.309 ± 0.181 in the SGA group and 0.348 ± 0.213 in the control group and was significantly lower in the SGA group. At/Et was 0.290 ± 0.007 in the TTN-positive SGA group, 0.313 ± 0.017 in the TTN-negative SGA group, and 0.351 ± 0.186 in the TTN-negative control group, a significant difference. Additionally fetal pulmonary artery At/Et was found to be inverse correlated with TTN. (-0,464 P = 0.000). The cut-off value of 0.298 provided optimal specificity of 93.0 % and sensitivity of 81.0 % for subsequent diagnosis of TTN in term SGA newborns in the neonatal period.

CONCLUSION: The risk for TTN increases in uncomplicated term SGA fetuses. The fetal pulmonary artery At/Et appears to be a noninvasive useful method by which to predict TTN in these fetuses.