[Perinatal factors associated with pH<7.1 in umbilical artery and Apgar 5 min <7.0 in term newborn]

To assess perinatal factors associated with term newborns with pH<7.1 in the umbilical artery and 5th min Apgar score<7.0.

Retrospective case-control study carried out after reviewing the medical records of all births from September/1998 to March/2008, that occurred at the General Hospital of Caxias do Sul. The inclusion criterion was term newborns who presented a 5th min Apgar score <7.0 and umbilical artery pH<7.10. In the univariate analysis, we used the Student's t-test and the Mann-Whitney test for continuous variables, the c² test for dichotomous variables and risk estimation by the odds ratio (OR). The level of significance was set at p<0.05.

Of a total of 15,495 consecutive births, 25 term neonates (0.16%) had pH<7.1 in the umbilical artery and a 5th min Apgar score <7.0. Breech presentation (OR=12.9, p<0.005), cesarean section (OR=3.5, p<0.01) and modified intrapartum cardiotocography (OR=7.8, p<0.02) presented a significant association with the acidosis event. Among the fetal characteristics, need for hospitalization in the neonatal intensive care unit (OR=79.7, p <0.0001), need for resuscitation (OR=12.2, p <0.0001) and base deficit were associated with the event (15.0 versus -4.5, p<0.0001).

Low Apgar score at the 5th min of life associated with pH<7.1 in the umbilical artery can predict adverse neonatal outcomes.