A risk stratification model to predict adverse neonatal outcome in labor

The development and evaluation of a labor risk model consisting of a combination of antepartum risk factors and intrapartum fetal heart rate (FHR) characteristics that can reliably identify those infants at risk for adverse neonatal outcome in labor.

A nested case-control study of term singleton deliveries at the nine hospitals between March 2007 and December 2009. Eligibility criteria included: gestational age ≥ 37.0 weeks; singleton pregnancy; documented continuous FHR monitoring for ≥ 2 h before delivery; assessment of FHR tracing at least every 20 min; and, available maternal and neonatal outcomes. Adverse neonatal outcome was defined as nonanomalous infants admitted to the newborn intensive care unit with either a 5 minute Apgar score <7 or an umbilical artery pH<7.1. Initial risk score was determined using data available at 1 h after admission. Patients with an initial risk score between 7 and 15 were considered high risk. Intrapartum risk scores were then created for these patients using FHR tracing data and labor characteristics.

A total of 51 244 patients were identified meeting study criteria. Of the antepartum variables evaluated (n=31), 10 were associated with an adverse outcome. The high-risk group made up 28% of the population and accounted for 59.8% of the adverse outcomes. Intrapartum characteristics were then evaluated in this high-risk group. Intrapartum evaluation identified the highest risk group with a C/S rate of 40% and adverse outcome rate of 11.3%.

Incorporation of maternal and antepartum risk factors with FHR analysis can improve the ability to identify the fetus at risk in labor.