Antepartum fetal asphyxia in the preterm pregnancy.

OBJECTIVE: The objective of this report was to provide insight into the frequency and characteristics of antepartum fetal asphyxia in pregnancies that are delivered preterm. STUDY DESIGN: The characteristics of 30 pregnancies that were delivered preterm with biochemically confirmed antepartum fetal asphyxia (umbilical artery base deficit of >12 mmol/L) that were derived from >1 decade of experience in a single tertiary care obstetric unit were examined. Antepartum clinical characteristics, fetal assessment tests, and neonatal complications were documented. Fetal asphyxia was classified as mild, moderate, or severe on the basis of an umbilical artery base deficit (>12 mmol/L) and newborn encephalopathy and other organ system complications. RESULTS: Antepartum fetal asphyxia accounted for at least 34% of the fetal asphyxia in the pregnancies that were delivered preterm. Predictive criteria that led to intervention and diagnosis included clinical risk factors and, particularly, abnormal fetal assessment tests. The 50% incidence of moderate or severe asphyxia in the antepartum preterm pregnancies compares with 15% in term pregnancies. Moderate or severe asphyxia occurred with equal frequency with early and delayed intervention. CONCLUSION: Fetal asphyxia in pregnancies that were delivered preterm is present frequently before the onset of labor. Abnormal fetal assessment tests are valuable predictors of antepartum fetal asphyxia. The increased frequency of moderate and severe fetal asphyxia in the pregnancy that is delivered preterm implies a greater likelihood of long-term morbidity or death.