Objective

Fewer than 50% of neonates with an umbilical arterial pH < 7.00 have neonatal complications. Our objective was to identify clinical predictive factors for adverse outcomes in this group of neonates.

Study design

In this case-control study both cases and controls had an umbilical arterial cord pH < 7.00. Cases were defined as those neonates who had seizures, grade 3 to 4 intraventricular hemorrhage, gastrointestinal dysfunction, respiratory distress syndrome requiring intubation, sepsis, or death. Controls had an umbilical arterial cord pH < 7.00 and no complications. A multivariable prediction model was created, with variables having an association with adverse outcome by bivariate analyses, attempting to predict which neonates in this umbilical arterial pH range are at greatest risk for adverse outcomes.

Results

We identified 73 of 10,705 neonates born between July 1992 and October 1996 with an umbilical arterial cord pH < 7.00. Thirty-five neonates met our case definition, and the remaining 38 composed the control group. Cases had significantly lower arterial pH values and 1- and 5-minute Apgar scores, greater arterial base deficit values, and a higher incidence of abruptio placentae and maternal cocaine use. More cases were delivered before 34 weeks. There were three neonatal deaths, two cases of grade 3 or 4 intraventricular hemorrhage, five cases of gastrointestinal dysfunction, and four cases of neonatal seizures. In our predictive model for adverse neonatal outcome, an arterial base deficit > or = 16 mmol/L and a 5-minute Apgar score < 7 had a sensitivity and a specificity of 79% and 80.8%, respectively.

Conclusion

Neonatal morbidity in neonates with an umbilical arterial cord pH < 7.00 can be predicted by a high arterial base deficit value and low 5-minute Apgar score.