Importance of electronic monitoring of intrapartum fetal heart rate as a predictor of neonatal outcomes

Introduction: acute fetal distress is a metabolic disorder leading to hypoxia and acidosis that can result in serious lesions and even death. It is one of the main causes for neonatal morbimortality. Objective: to determine the relationship between the different fetal heart rate patterns corresponding to the suspicion of fetal hypoxia and neonatal results. Method: a prospective study (November 2001-August 2004) was conducted at the Maternity Service of the Pereira Rossell Hospital. Population: 183 patients were selected according to the following inclusion criteria: single pregnancy, cephalic presentation, labor and electronic monitoring of the fetal heart rate indicating fetal hypoxia. Pregnancy was interrupted in all emergency cases once diagnosis had been made. Results: average time for diagnosis at birth was 16.97 minutes, with a standard deviation of 7.7 minutes. Diagnostic patterns were: intra-partum deceleration 2 (106 cases, 58%), persistent bradychardia (79 cases, 43%), decrease in variability (12 cases, 6%), not promising (complex varied deceleration curves, 12 cases, 6%). Taking the acid-base state as a neonatal variable, the patterns that best predict the perinatal condition for pH levels below 7.10 is fetal bradychardia, representing positive predictive value of 31.6 (predictive value of the positive test). Taking into account the need to refer the newborn to the neonatal care unit, the pattern that best predicts this fact is a decrease in variability of 41.7(positive predictive value). Conclusion: the methods used in the study to diagnose intra-partum hypoxia have low positive predictive values.