Short term variability of fetal heart rate during insulin-dependent diabetic pregnancies

The clinical significance of quantified short term variability of antepartal fetal heart rate (FHR) in prediction of fetal distress in labor was assessed in 120 insulin-dependent diabetic pregnancies. FHR was recorded by abdominal fetal electrocardiography (aFECG), from which the differential indices (DI) describing the short term variability of FHR were analyzed by a microprocessor-based on-line method. The analysis was successful in 308 of 350 trials (87%). In ten pregnancies, no acceptable a FECG was obtained. Fetal distress developed in 28 of the 110 pregnancies with successful FHR analysis. There were no intrauterine deaths in this series, but two newborn infants died (perinatal mortality 1.7%). Ninety-three pregnancies with FHR analyses within one week of delivery were included in the assessment of the test. DI predicted 2 of the 17 cases of fetal distress (sensitivity 67%). Twelve of the 18 cases with a pathological DI developed fetal distress (predictive value 71%). DIs were normal in 67 of the 73 pregnancies without fetal distress (specificity 92%). Risk of fetal distress after a pathological DI was 8.5 times that after normal DIs (relative risk), which is highly significant.