Utility of Umbilical Arterial Blood Gas Lactate Levels in Predicting Short-term Neonatal Morbidity: A Retrospective Audit in a Tertiary Neonatal Unit

Background:Umbilical cord arterial lactate is a surrogate marker for fetal hypoxia. A poor cord lactate often portends poorer neurological outcomes. Currently, there is no universally accepted threshold for normal cord lactate. Methodology:A retrospective case-control study of 1978 neonates born in a tertiary women's and children's hospital with a neonatal intensive care unit was conducted from July 1, 2022, to December 31, 2022. The primary outcome was evaluating the utility of arterial lactate to predict neonatal outcomes. Secondary outcomes included comparing institution guidelines with that of the American College of Obstetricians and Gynecology (ACOG) to determine cutoff thresholds for arterial pH, base excess (BE), and lactate to aid in risk stratification. Results:Cord blood arterial lactate was not a statistically significant predictor of poor neonatal outcomes (odds ratio [OR]: 1.09, [95% confidence interval (CI): 0.84-1.41], P = 0.5320). Babies who are delivered by crash cesarean section (OR: 3.96, [95% CI: 1.11-14.23], P = 0.0343), needed urgent resuscitation at birth (OR: 4.79, [95% CI: 1.63-14.06], P = 0.0044), with poor 1-min Apgar score (OR: 0.62, [95% CI: 0.49-0.78], P < 0.0001) or 5-min Apgar score (OR: 0.12, [95% CI: 0.04-0.37], P = 0.0002), higher venous BE (OR: 0.77, [95% CI: 0.65-0.92], P = 0.0034), or higher venous lactate (OR: 1.43, [95% CI: 1.12-1.82], P = 0.0043) had poorer outcomes. An arterial pH < 7.024, an arterial BE >=-11.6 mmol/L, and an arterial lactate >= 8.4 mmol/L were deemed optimal cutoffs to predict a poorer neonatal outcome. Both ACOG and our institutional guidelines shared a similar predictive ability to identify neonates with poor cord gases at risk of poor outcomes. Conclusion:Although umbilical cord arterial lactate was not a statistically significant predictor of short-term neonatal morbidity, its clinical utility in predicting poor outcomes alongside maternal, fetal risk factors, and other biochemical indices on the cord blood gas, should not be undervalued.