Is there a correlation between time of delivery and newborn cord pH?

Since more senior and attending physicians work in labor wards during morning shifts, we expect a better delivery outcome during that time period.

A retrospective study was conducted between 1/2005 and 12/2014. Records of 56 428 singleton deliveries from a tertiary hospital in which cord blood pH was routinely measured at birth were analyzed. Time of birth was divided into shifts: 7 AM-3 PM (morning shift), 3 PM-11 PM (afternoon shift), and 11 PM-7 AM (night shift). Additional stratification compared weekdays and weekend deliveries.

19 601, 18 429, and 18 398 neonates were born during morning, afternoon, and night shifts, respectively. There was no significant difference in maternal age, neonatal weight, or mean 5-min Apgar score among the three shift periods. Furthermore, there was no correlation between shift time of delivery and newborn acidosis with respect to cord pH less than 7 (0.1% in each time periods, p = 0.67). Despite the above, instrumental deliveries and cesarean sections were more common in the morning shift compared to the afternoon and night shift, respectively (p = 0.001 each).

Although shift time of delivery was found to be related to mode of delivery it was not related to either 5-min Apgar score or newborn acidosis as reflected by cord pH.