AT THE PREGNANCY MEETING
SAN DIEGO (FRONTLINE MEDICAL NEWS) – The use of electronic fetal monitoring is ubiquitous in the United States, but a case-control study shows that monitoring patterns do not differ between term infants with evidence of brain injury on magnetic resonance imaging and those without injury.
Of 220 apparently normal term infants who underwent MRI, 25 had injury identified by the MRI, including 23 with mild injury, 1 with moderate injury, and 1 with severe injury. None of several electronic fetal monitoring characteristics – including moderate, minimal, marked, or absent variability, or late, prolonged, or variable repetitive decelerations – predicted injury, Dr. Alison Cahill reported at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.
The researchers also did not find a significant association between the injuries and several clinical factors known to increase the odds of injury, such as cesarean delivery (odds ratio, 1.8), nulliparity (OR, 1.0), acidemia (OR, 2.8), and labor induction (OR, 0.7).
The study results are based on findings at both 30 and 60 minutes prior to delivery.
Although white race and a complete absence of moderate variability on EFM in the 1-2 hours prior to birth were more common in those with injury, the predictive value of these factors alone was poor, said Dr. Cahill of Washington University, St. Louis.
The patients included in this study were from a prospective cohort of 8,340 women with vertex anatomically normal singleton pregnancies, who were in labor after at least 37 weeks’ gestation.
Case infants had an arterial cord gas pH less than 7.10, and control infants were temporally-, age-, and sex-matched infants with a normal arterial cord gas pH of 7.20 or greater. All infants underwent nonsedated MRI between 24 and 72 hours after birth.
The MRI findings were independently interpreted by a pediatric neuroradiologist and intensivist, who were blinded to clinical data and patient outcomes, and EFM patterns were interpreted by obstetric research nurses who were blinded to clinical outcomes, Dr. Cahill said.
Cerebral MRI has become the clinical imaging modality of choice for preterm infants and those with hypoxic-ischemic encephalopathy (HIE), because MRI findings in these populations have been correlated with neonatal outcomes, and enable increased surveillance and early intervention, she said.
However, more than three-quarters of neurologic disability occurs among infants born after 36 weeks without HIE, she said.
The aim of the current study was to characterize neurologic injury in neonates and term infants without HIE, and to identify intrapartum EFM patterns and peripartum risk factors for injury. But no such risk factors emerged, she said.
Though limited by the inherent subjectivity in EFM and MRI interpretation, the study involves the largest cohort to date in which the ability of clinical and EFM characteristics to predict brain injury is examined, Dr. Cahill said.
“We believe it is important to acknowledge the limitations of our clinical ability to use EFM based on our current knowledge and the manner in which we use it at the bedside,” she said. “Clinicians cannot predict brain injury in apparently normal term infants with EFM patterns preceding birth.”
The study was supported by a grant from the National Institute of Child Health and Human Development. Dr. Cahill reported having no relevant financial disclosures.
