Correlation between umbilical cord blood pH and meconium stained deliveries

Abstract

Background: Among all live births approximately 13% neonates are born through meconium-stained amniotic fluid and out of these 5-10% developed MAS, which increases neonatal morbidity and mortality. The incidence increases as the gestational age advances with reported frequencies at 37, 40, and >42 weeks being 3%, 13%, and 18% respectively. Although there is a significant decrease in the occurrence of MAS and associated mortality in developed countries, MAS remains a major problem in developing countries. The objective was to study the correlation between umbilical cord blood PH and Meconium stained amniotic fluid.Methods: Observational study done in KIMS hospital Bangalore, Karnataka, India in a study period of 18 months on a sample size of 100. Within 30 sec of delivery a segment of umbilical cord was clamped at both ends. Cord blood was collected in heparinised syringe. It was then transported with cold ice packs and blood pH, pCO2, pO2 were measured.Results: In present study population, among those with MSAF, 72% had acidemia and 28% did not have acidemia. The mean (SD) of pH in the group with MSAF was 7.16 (0.10). The median (IQR) of pH in the group with MSAF was 7.14 (0.12). There was no significant difference between the groups (those with MSAF and those without MSAF but other risk factors) in terms of pH (W = 867.500, p = 0.580).Conclusions: The presence of acidosis in the umbilical cord blood, used as a biochemical marker for perinatal asphyxia can be used to evaluate the significance of intrauterine passage of meconium. But a normal acid-base status at delivery present in many cases of MSAF, suggests that either a pre-existing injury or a non-hypoxic mechanism is often involved. MSAF is not always secondary to an acute hypoxic event.