Intrapartum asphyxia in pregnancies complicated by intra-amniotic infection

Intra-amniotic infection has been reported to be associated with intrapartum asphyxia; however, the criteria used to define asphyxia have been imprecise. In the present study of 123 women with intra-amniotic infection and 6769 women without infection, the mean umbilical artery pH was 7.28 in both groups. The frequency of acidemia (umbilical artery pH less than 7.20) was not significantly different between the infection group and controls (15 versus 10%; P = .12). Likewise, there was no significant difference between the groups when a lower umbilical artery pH value (less than 7.15) was used to define acidemia. None of the infants from infected mothers had metabolic acidemia with a pH of less than 7.15 and none had a pH of less than 7.00. Significantly more (P less than .05) infants in the infected group did have low 1-minute (20 versus 5%) and 5-minute (3 versus 1%) Apgar scores of 6 or less, criteria often used to define asphyxia. However, none of the newborns from the infected group had recently proposed criteria for the diagnosis of birth asphyxia (ie, leading to neurologic impairment) such as metabolic acidemia, seizures in the immediate newborn period, and low Apgar scores (3 or less). Birth asphyxia is rarely associated with intra-amniotic infection, and in the absence of other signs of fetal jeopardy such as an ominous fetal heart rate pattern, an immediate cesarean to prevent asphyxia does not appear justified once the diagnosis of chorioamnionitis is made.