Low Apgar scores and umbilical cord acidosis in preterm infants

LOCATELLI, ALESSANDRO GHIDINI, FRANCESCA ASSI, MADDALENA INCERTI, VALENTINA DORIA, CLAUDIA BONARDI, GIUSEPPE PATERLINI, University ofMilan-Bicocca, Obstetrics andGynecology,Monza, Italy, University ofMilan-Bicocca, Neonatology, Monza, Italy OBJECTIVE: To evaluate whether in preterm infants, cases of low Apgar scores associated with acidosis have distinguishing characteristics compared with those without acidosis. STUDY DESIGN: From a cohort of 653 consecutive singleton neonates born after spontaneous or iatrogenic preterm delivery at 24.0-33.6 weeks from 1/ 1993 to 12/2002 we selected those with 5-minute Apgar score !7. Demographic, obstetric (gestational age, pregnancy complications, mode of delivery), neonatal (sex, weight, unfavorable outcome) and placental histology variables were evaluated in reference to umbilical artery evidence of fetal acidemia, defined as pH !7.10. Excluded were stillbirths and congenital anomalies. Statistical analysis included Spearman’s correlation, Fisher’s exact test and Student t-test with P!0.05 considered significant. RESULTS: We observed a significant correlation between Apgar score at 5 minutes and pH of umbilical artery (R = 0.5356, p!0.001). A 5-minute Apgar score !7 was recorded in 70/653 (10.7%) infants born at !34 weeks, and 13 of them (19%) had umbilical artery gas analysis suggestive of acidosis. Acidotic babies differed from non-acidotic babies with low 5-minute Apgar score in rates of indicated prematurity (69% vs 31%, P=0.02) and presence of vascular placental lesions (69% vs 29%, P=0.02) but not in rates of obstetric complications, labor, delivery, and neonatal characteristics and complications. CONCLUSION: Preterm deliveries at !34 weeks with 5-minute Apgar scores !7 are at increased risk for acidosis if prematurity is obstetrically indicated and placenta pathology shows evidence of vascular lesions.