The effect of fetal sepsis on umbilical cord blood gases

The relationship between fetal sepsis and acid-base status is unknown. We hypothesized that in utero sepsis would result in fetal metabolic acidemia. In a retrospective study during a 38-month period, the acid-base status at birth of neonates with in utero sepsis, documented by positive blood cultures, was reviewed. Compared with term neonates, preterm neonates had a 22-fold increase in the risk of bacteremia at birth. In spite of this increased risk of sepsis, there was no significant alteration in arterial pH in preterm septic neonates when compared with preterm controls. Fetal sepsis at term was accompanied by a statistically significant reduction in arterial pH (7.21 ± 0.07) compared with controls (7.26 ± 0.06, p < 0.05). When controlled for other variables, the decrease in arterial pH at term was correlated with an increased duration of labor (7.3 ± 0.7 in controls vs 10.8 ± 0.9 hours in neonates with sepsis, p < 0.05). The classic predictors of chorioamnionitis were found to be poor prognostic indicators of fetal bacteremia. Fetal sepsis at term is associated with a deterioration in the fetal acid-base status and a prolongation of labor.