To estimate whether fetal bradycardia-to-delivery interval or decision-to-delivery interval was related to cord arterial pH according to different causes of fetal distress. Women who delivered singleton neonates by urgent cesarean delivery because of intrapartum fetal bradycardia were retrospectively categorized into three groups according to the cause of fetal bradycardia: 1) Irreversible; 2) Potentially Reversible; and 3) Unknown (no identifiable cause). Comparisons were made between groups in regard to pH, bradycardia-to-delivery interval, and decision-to-delivery interval. Correlation analyses between pH and both intervals were then performed for different groups. Of 235 cases, 39, 22, and 174 were respectively categorized into the Irreversible group, Potentially Reversible group, and Unknown group. The median pH was lower in the Irreversible group (7.094; interquartile range [IQR] 6.991-7.216) than in Potentially Reversible group (7.162; IQR 7.064-7.251) or Unknown group (7.210; IQR 7.161-7.255) (P<.001). The Irreversible group's median bradycardia-to-delivery interval was 5 minutes shorter than those of the other two groups (11 compared with 16.5 and 16 minutes, respectively; P<.001), whereas its median decision-to-delivery interval was 1 minute shorter (10 compared with 11.5 and 11 minutes, respectively; P=.001). In the Irreversible group, pH decreased with the bradycardia-to-delivery interval (Spearman's rho=-0.354; P=.027) at a rate of 0.011 per minute. Cord arterial pH did not correlate with the bradycardia-to-delivery interval in the Potentially Reversible and Unknown groups. In neither group did pH correlate with decision-to-delivery interval. Cord arterial pH deteriorates with bradycardia-to-delivery interval when the underlying cause of fetal distress is irreversible, but not so otherwise. II.