Normal Fetal Heart Rate Pattern in the Brain-damaged Infant: A Failure of Intrapartum Fetal Monitoring?

Abstract

> Objective: To describe the perinatal characteristics of neurologically impaired infants with normal intrapartum fetal heart rate (FHR) patterns. Methods: In a registry of 300 neurologically impaired singleton term infants, a retrospective chart review was undertaken to analyze those patients with a normal intrapartum FHR pattern, i.e. reactive FHR pattern with a normal baseline rate throughout labor, and a subsequent finding of central nervous system impairment. Neonates with an abnormal intrapartum FHR pattern or a traumatic birth were excluded. In addition, the four criteria necessary for intrapartum asphyxia were as follows: arterial pH <7.00, Apgar score </=3 for 5 min, neonatal neurologic sequelae, such as seizures, and multiorgan system dysfunction. Infants were then categorized according to the timing of probable fetal injury. Results: Of the 300 infants in the registry, 24 (8%) neonates were identified. Six (25%) of these were considered postdates. Primary antenatal complications included early pregnancy bleeding (3 (13%)), cigarette and/or alcohol use (4 (17%)), and polyhydramnios (2 (8%)). Meconium was found in 12 patients (50%) during labor; of these, two (8%) patients had meconium aspiration syndrome and required extra corporeal membrane oxygenation (ECMO). None of the infants satisfied the four criteria for intrapartum asphyxia. Sixteen (67%) neonates were discharged with their mothers. The remaining eight neonates were admitted to the neonatal intensive care unit, and two (8%) neonatal deaths occurred due to meconium aspiration syndrome and sudden infant death syndrome. The long term neurologic outcome of the 22 survivors ranged from 3 to 14 years and included the following: developmental delay (10 (45%)), seizure disorder (7 (32%)), cerebral palsy (11 (50%)), and mental retardation (4 (17%)). None of these infants appeared to have been injured during labor. The probable timing of neurologic injury appeared to be early pregnancy (13 (54%)) or postnatally (11 (46%)). Conclusions: Infants who are later found to be neurologically impaired can have normal intrapartum FHR patterns during labor. These neurologic injuries seem to occur in early pregnancy or after birth. In the absence of fetal trauma, these findings suggest that a reactive intrapartum FHR pattern is not associated with intrapartum fetal asphyxia.