Correlation between the Assessment of Fetal Well-being, Umbilical Artery pH at Birth and the Neonatal Results in High-risk Pregnancies - Revista Brasileira de Ginecologia e Obstetrícia

Purpose: to analyze the relationship between the values of pH at birth, fetal surveillance examinatios and neonatal results. Methods: one thousand, three hundred and forty-six high-risk pregnancies were evaluated at the Fetal Surveillance Unit. The assessment of fetal well-being included cardiotocography, fetal biophysical profile and amniotic fluid index. After birth, the perinatal results (gestational age at birth, birth weight, Apgar scores at 1st and 5th minutes, umbilical cord pH at birth) were collected. To study the results, the patients were divided into four groups: G1 (pH <7.05), G2 (pH between 7.05 and 7.14), G3 (pH between 7.15 and 7.19) and G4 (pH > or = 7.20). Results: the abnormal patterns of cardiotocography were associated with pH at birth inferior to 7.20 (p = 0.001). Abnormal results of the fetal biophysical profile (<=4) were related to decrease in pH values at birth (p<0.001). The adverse neonatal outcomes were associated with acidosis at birth, and they were selected to be analyzed by the logistic regression model, showing that the odds ratio of each adverse neonatal outcome increases significantly when the values of pH at birth decrease. Conclusions: significant correlation was found between the values of pH at birth and adverse neonatal results, providing the possibility to estimate the risk of neonatal complications according to the pH values at birth.