How Much Milk Fits: A Feed-Volume Schedule from Gastric Capacity in the First Weeks of Life

Feeding charts for newborn infants commonly state a volume per feed, or a volume per kilogram, with little indication of where the number came from or whether the stated volume can physically fit in the stomach of an infant of that age. This paper derives a feed-volume schedule from the other direction: from a stated model of gastric capacity. Capacity per kilogram is taken to rise from 2.0 mL/kg on the day of birth to 32.0 mL/kg by day 21; each feed is scheduled to fill at most 75% of modelled capacity; the daily milk volume follows from an age-banded energy requirement divided by a milk energy density of 0.67 kcal/mL, the same for breast milk and standard formula; and scheduled feeds are capped at 12 per day. The derived schedule runs from 12 feeds of 4.9 mL on day 0 to 7 feeds of 108.2 mL on day 28. On days 0 to 3 the schedule is capacity-limited: meeting the stated energy requirement within the capacity ceiling would require 30, 20, 16, and 14 feeds per day respectively, so even at 12 feeds per day the model delivers 59.8%, 60.3%, 76.7%, and 86.1% of the required volume on those days, a shortfall the paper reports rather than removes. The schedule first meets the full requirement on day 5, at 12 feeds of 37.5 mL. A flat rule of 20 mL per kilogram per feed, applied at all ages, overshoots modelled capacity by a factor of 10.0 on day 0, 5.0 on day 1, 2.0 on day 3, and 1.25 on day 5; it first fits within total capacity on day 7 and first fits within the 75% ceiling on day 14. A single per-kilogram feed figure therefore cannot be correct across the first weeks of life: any such figure that is reasonable at two weeks is physically impossible in the first days.