The Effect of mode of delivery on the umbilical artery pH

Background: Abnormal umbilical cord pH can be indicated a distress imposed of newborn and can also be useful in determining the prognosis of the newborn. There are different views about the effect of the neonatal delivery method on the blood gas analysis of the umbilical artery. This study aimed to determine the effect of the method of delivery on umbilical artery pH. Methods: In this Cross-Sectional study, 150 singleton newborns of 37 to 42 weeks, with birth weight 2500 to 4000 g, were allocated. The samples were calculated for values, based on similar studies, and were divided into two groups, including vaginal delivery and caesarian section under spinal anesthesia which have the least difference in pH. Umbilical artery blood gas analysis of both groups were studied. Finally, using statistical T-test for the quantitative data and chi-square for the qualitative data, hypotheses were answered. P-value less than 0.05 was considered statistically significant. Results: Average gestational age was between 39±0.9 weeks and 76 (50.6%) and 74 (49.4%) of neonates were male and female respectively. The average birth weight was 3368.7±473.5 g. In this study, average umbilical artery pH at birth by vaginal delivery and by cesarean section was 7.25±0.06, 7.26 ±0.06 respectively (P>0.05). In this study, in both groups significant differences were seen in all the blood gas values except the umbilical cord artery pH. Conclusions: Our study showed that the pH level of umbilical artery blood was in normal range among newborns of both groups, but Po2 and Pco2 were more appropriate in vaginal deliveries. Due to the prognostic value of umbilical artery PH and the essentiality of prognosis in the newborns under stress, we recommend that this study should be done in the emergency situation, too.