Pathological fetal heart rate tracing patterns and neonatal outcomes among parturients beyond 32 weeks of gestation: a prospective observational study.

Purpose: Distinct clinical phenotypes of pathological fetal heart rate (FHR) tracings may affect neonatal outcomes differently. This study aimed to determine and differentiate neonatal outcomes amongst the clinical phenotypes of pathological FHR tracing.

Methods: This prospective observational study included women in labour with pathological fetal heart rate tracing during delivery. Pathological fetal heart rate tracings were characterized into 11 clinical phenotypes and corresponding neonatal and maternal outcomes were recorded. Neonates and mothers were followed till discharge from the hospital. The primary outcome was a 5-min Apgar score. The secondary outcomes were NICU admission, mode of delivery, mode of anesthesia, neonatal morbidity and mortality.

Result: 271 women with pathological fetal heart rate tracing at the time of delivery were included in the study. Most of the women (64%) underwent cesarean delivery. The most common pathological fetal heart rate tracing was repetitive late decelerations (24.7%), followed by reduced variability with repetitive variable decelerations (24.4%). The 5-min Apgar score was comparable across all clinical phenotypes of pathological fetal heart rate tracing. Tachycardia with reduced variability was associated with a significantly higher likelihood of NICU admission (aOR 5.03, 95% CI 1.32-19.27, p = 0.018). Reduced variability, repetitive late decelerations and the combination of repetitive late decelerations with prolonged decelerations and reduced variability showed moderately increased odds of NICU admission.

Conclusions: The 5-min Apgar score remained comparable in all clinical phenotypes of pathological fetal heart rate tracing. Nonetheless, the odds of NICU admission were significantly higher in women with tachycardia and reduced variability.