Correlation of fifth-minute Apgar score, umbilical cord blood pH, and nucleated red blood cell count in depressed and non-depressed term neonates in Lagos, Nigeria

In low-resource settings such as Nigeria, assessment of perinatal hypoxia relies heavily on the Apgar scoring system, which is subjective and may be influenced by factors unrelated to hypoxic insult. Umbilical cord blood pH provides a more objective measure of hypoxia but is often unavailable. Nucleated red blood cell (nRBC) count has been suggested as a laboratory marker associated with fetal hypoxia. Comparative evaluation of these indices may improve understanding of their relationships in neonates without perinatal depression and neonates with perinatal depression. To compare umbilical cord blood pH, nucleated red blood cell count, and fifth-minute Apgar scores between depressed and non-depressed term newborns in Lagos, Nigeria. A comparative cross-sectional study was carried out in Lagos, Nigeria between May 2018 and March 2019 involving 126 term neonates, comprising 63 neonates with perinatal depression (Apgar score < 7 at 5 min) and 63 controls without perinatal depression (Apgar score ≥ 7). Umbilical cord blood samples were collected at birth for pH analysis, while peripheral venous blood samples obtained at 6–8 h of life were used to determine nucleated red blood cell counts. Fifth-minute Apgar scores were documented for all participants. Comparative and correlation analyses were performed. Neonates with perinatal depression had a significantly lower mean umbilical cord blood pH compared with and neonates without perinatal depression (7.24 ± 0.10 vs. 7.30 ± 0.07; p < 0.001). Median nucleated red blood cell count was significantly higher among neonates with perinatal depression (3 vs. 2 nRBC/100 WBC; p = 0.001). Fifth-minute Apgar scores showed a significant positive correlation with cord blood pH (ρ = 0.47) and a significant negative correlation with nucleated red blood cell count (ρ = −0.45). The correlation between nucleated red blood cell count and cord blood pH was negative but not statistically significant (ρ = −0.23). Term newborns neonates with perinatal depression demonstrated significantly lower umbilical cord blood pH and higher nucleated red blood cell counts compared with neonates without perinatal depression. Fifth-minute Apgar scores correlated significantly with both cord blood pH and nucleated red blood cell count, highlighting important relationships among clinical and laboratory indicators of perinatal hypoxia.