Little is known about the ontogeny of gastric acid secretion in the ve
ry preterm infant. In order to study this we recorded intragastric pH
continuously for 24 h on 71 occasions in 22 enterally starved preterm
infants. Infants ranged from 24 to 29 weeks' gestation and were studie
d in the first 5 days, and in the third week, of life. As the infants
became more mature, both in terms of gestation and postnatal age, ther
e was a decrease in intragastric pH from median (range) 3.7, 2.5 (0.6-
3.9) and 1.8 (1.3-2.6) for infants of 24-25, 26-27 and 28-29 weeks' ge
station, respectively on the first day of life to 1.8 (1.7-1.9), 2.0 (
1.8-2.3) and 1.7 (1.5-2.0) on day 16. All the infants were able to mai
ntain a gastric pH of below 4 from the first day of life. Our data lay
to rest the suggestion that the preterm infant is incapable of hydrog
en ion secretion. Gastric acid secretion in the newborn preterm infant
should allow normal proteolytic activity and the well recognised clin
ical problems of intragastric bleeding, gastritis or oesophagitis may
be attributable to intragastric acid.