Background:  Current evidence suggests that umbilical arterial pH analysis provides the most sensitive reflection of birth asphyxia. However, there’s debate whether umbilical cord blood gas analysis (UC‐BGA) should be conducted on some or all deliveries.
Aim:  The aim of this study was to evaluate the impact of introducing universal UC‐BGA at delivery on perinatal outcome.
Methods:  An observational study of all deliveries ≥20 weeks’ gestation at a tertiary obstetric unit between January 2003 and December 2006. Paired UC‐BGA was performed on 97% of deliveries (n = 19,646). Univariate and adjusted analysis assessed inter‐year UC‐BGA differences and the likelihood of metabolic acidosis and nursery admission.
Results:  There was a progressive improvement in umbilical artery pH, pO2, pCO2, base excess and lactate values in univariate and adjusted analyses (P < 0.001). There was a significant reduction in the newborns with an arterial pH <7.10 (OR = 0.71; 95%CI 0.53–0.95) and lactate >6.1 mmol/L (OR = 0.37; 95%CI 0.30–0.46). Utilising population specific 5th and 95th percentiles, there was a reduction in newborns with arterial pH less than 5th percentile (pH 7.12; OR = 0.75; 95%CI 0.59–0.96) and lactate levels greater than 95th percentile (6.7 mmol/L; OR = 0.37; 95%CI 0.29–0.49). There was a reduction in term (OR = 0.65; 95%CI 0.54–0.78), and overall (OR = 0.75; 95%CI 0.64–0.87) nursery admissions. These improved perinatal outcomes were independent of intervention rates.
Conclusions:  These data suggest that introduction of universal UC‐BGA may result in improved perinatal outcomes, which were observed to be independent of obstetric intervention. We suggest that these improvements might be attributed to provision of biochemical data relating to fetal acid‐base status at delivery influencing intrapartum care in subsequent cases.