This study was undertaken to determine the relationship of umbilical cord pH and base excess (BE) values to adverse neonatal outcomes for a large tertiary hospital population delivering at term. Study design The perinatal/neonatal database of St. Joseph's Health Care, London, Canada, was used to obtain the umbilical cord pH and BE values, incidence of adverse neonatal outcomes, and patient demographics for all term (>/=37 weeks' gestation), singleton, liveborn infants with no major anomalies delivering between November 1995 and March 2002 (n=20,456). Statistical analyses included chi(2) analysis, logistic regression models to develop odds ratios and creation of receiver operating characteristic (ROC) curves with area under curve (AUC) calculations.