Umbilical vein white blood cell count as a marker of acidemia in term neonates

White blood cells are mobilized under both hypoxic and infectious conditions. Intrauterine hypoxia is linked to increased risk of cerebral palsy and is potentiated by the presence of infection. We hypothesized that umbilical vein white blood cell elevation in term neonates is associated with intrauterine acidemia.

We prospectively evaluated all liveborn neonates delivered at our institution for a 6-month period. Umbilical arterial blood was analyzed for pH and blood gas and venous blood for hematologic indices. Medical records of cases greater than or equal to 37 weeks' gestation were reviewed for correlative data. Student's t-test was used to determine difference of means and Chi-square test for goodness of fit. Pearson coefficients of correlation were applied where appropriate.

A total of 1,948 liveborn, term neonates were delivered during the study period; 1,561 cases had white blood cell analysis and arterial blood gas data available. Acidemic cases had higher white blood cell (15.0 vs. 12.4 cells x 10(3)/mm3, P < 0.001), lymphocyte (4.43 vs. 3.59 cells X 10(3)/mm3, P < 0.0001), and neutrophil counts (9.08 vs. 7.71 cells x 10(3)/mm3, P < 0.01). As umbilical artery pH decreased, white blood cells became more prevalent. Likewise, as base deficit deepened, white blood cell counts increased.

This study demonstrates an association between deepening acidemia and increasing white blood cell, lymphocyte, and neutrophil counts. Although statistically different, mean white blood cell counts for acidemic and nonacidemic cases are fairly close, limiting the clinical applicability in determining whether pathology is present in an individual case.