Progression of Gastric Acid Production in Preterm Neonates: Utilization of In-vitro Method.

Background: Limited studies are done regarding ability to produce gastric acid in preterm infants and most studies used in vivo method of assessing gastric pH. Objectives: To assess the feasibility of using an in vitro method of measuring gastric pH in babies ≤ 28 weeks gestational age (GA) and determine whether changes in gastric pH differ with gestational age, mode of delivery, and use of antenatal steroids. Design/Methods: Prospective study that enrolled extremely low birth weight (ELBW) babies. Gastric aspirate collected before feeding. In vitro testing of gastric aspirates for pH were done on days of life 1, 3, 5, 7, 14, and 28 by using pH electrode. The pH was measured on each sample in triplicate, mean calculated and used for data analysis. Stastical methods included descriptive statistics, t-tests and repeated measures ANOVA. Results: 29 subjects ≤ 28 weeks or birth weight ≤ 1,000 g were enrolled. No significant change was noted in pH measurements over time. Antenatal steroids and mode of delivery did not affect gastric acid pH. Conclusion: The in vitro method for gastric pH measurements is non-invasive and affords more frequent testing. It would be useful in studying various conditions that may affect gastric pH.