Background Intrapartum monitoring aims to identify fetal acidaemia. The fetal acidaemia threshold, reliably accountable for neonatal morbidity, or mortality, is less clear. The International Cerebral Palsy and American Congress of Obstetrics and Gynaecology task force, suggests: “pH <7 …. provides sufficient evidence to blame acute intrapartum events for the neonatal condition”.

Objective We analysed early neonatal outcomes in babies born with an arterial pH ≤7.1, from paired umbilical cord gases.

Method Retrospective case notes audit at Kingston hospital maternity unit, involving 30 singleton live neonates, between 01/01/2012–31/12/2012. Neonatal outcomes were assessed using: 5 min APGAR scores <7, need for resuscitation and neonatal unit (NNU) admissions.

Results Median arterial pH was 7.07, interquartile range 7.00–7.09. Neonates with an arterial pH 6.80–7.02 demonstrated; 100% resuscitation requirements and NNU admission; with 25% APGARs at 5 min <7. Above an arterial pH 7.02; absolute risk for resuscitation was 50%; 36.36% required NNU admission and 9.09% had APGARs at 5 min <7. No ideal arterial pH was identified for good neonatal outcomes. We compared our results against a large cohort study;¹ their threshold pH for adverse neurological outcomes was 7.10 and the ‘ideal’ cord pH 7.26–7.30.

Conclusion Overall, our results suggest an unpredictable association between acidaemia and adverse early neonatal outcomes, with a pH >7.02. Highlighting the multifactorial nature of predicting neonatal outcome; which if better understood, will improve interpretation of intrapartum monitoring.

Reference

1. Yeh P, Emary K, Impey L. The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51,519 consecutive validated samples