Fetal heart rate monitoring category 3 during the 2nd stage of labor is an independent predictor of fetal acidosis

Objective: To determine whether fetal heart rate (FHR) monitoring categories during the 1st and 2nd stage of labor can predict arterial cord pH <7.2. Materials and methods: A case control study was conducted including 653 consecutive term deliveries (37 weeks gestation and above) that were divided according to fetal pH <= 7.2 (n = 315) and fetal pH>7.2 (n = 338). Deliveries occurred during the year 2013 in tertiary medical center, where arterial cord pH is routinely taken after birth. Intrapartum FHR monitoring categorization was defined according to the ACOG committee guidelines by two obstetricians. Multivariable models were constructed to control for confounders. Results: Variable decelerations, late decelerations and bradycardia during the 1st and 2nd stages of labor were significantly higher in group of deliveries ended in cord pH<7.2 compared with group of deliveries ended in cord pH>7.2. A significant association was observed between category 2 and 3 during the 1st stage of labor and pH <= 7.2. However, while controlling for FHR category 3 at the 2nd stage of labor, 1st stage categorization lost its association with pH<7.2, and only category 3 during the 2nd stage were noted as an independent risk factor for acidosis. Conclusion: FHR monitoring category 3 during the 2nd stage of labor is an independent predictor of fetal acidosis as expressed by arterial cord pH<7.2.