Correlation of Apgar Score and Umbilical Artery pH in Full-Term Newborns Delivered by Cesarean Section Due to Decreased Fetal Heart Rate

Despite the high efficacy of the Apgar score in finding respiratory distress, a low Apgar score doesn’t necessarily indicate fetal hypoxia-asphyxia. Umbilical Artery pH (UApH) is one of the best indicators of fetal hypoxia. Therefore, it’s so beneficial to consider these criteria and their relationship with the Apgar score for accurate diagnosis of prenatal respiratory distress retrospectively which reduces the unnecessary cesarean section (CS) rate.

162 full-term (≥259 days) neonates delivered by CS with the diagnosis of decreased fetal heart rate (FHR) were evaluated. 1-min and 5-min Apgar scores and UApH were measured. The correlation between Apgar scores with UApH and the association between UapH and Apgar with the NICU admission were evaluated. The effect of other variables including mother’s age, gravidity, gestational age, birth weight, newborn sex, and causes of decreased FHR on Apgar scores and UApH were studied as well.

The most common cause of decreased FHR was fetal distress, boys had higher weight (P=0.033) and lower UApH (P=0.049) than girls. Other parameters were not different significantly between both sexes. There was a positive correlation between UApH and 1-min and 5-min Apgar scores (r=0.464 and r=0.370 respectively) when controlled for birth weight (P<0.0001). The RR for NICU admission in male acidemic neonates with abnormal 1-min Apgar was 14.05 (CI95%: 5.7-34.6) in comparison to females (RR=1.06, CI95%: 1-1.26).

Mild acidemia (UApH<7.2) at least in a male fetus would be a good predictor for postnatal complications and need for NICU admission. Future studies with more samples are suggested.