Why does formula feeding lead to gradual hypertrophy of the pylorus?

The gradual hypertrophy of the pylorus in infants who are formula-fed can be attributed to the characteristics of formula feeding. Formula is typically designed to provide a higher volume of nutrition compared to breast milk. This results in larger feedings at once.

When infants are fed formula, they often take in more volume of food which leads to increased pressure and stimulation in the pylorus, the area where the stomach connects to the small intestine. The consistent larger volumes combined with the need for the pylorus to manage these amounts can contribute to hypertrophy, or thickening, of the pyloric muscle.

Furthermore, formula feeding can affect the gastric emptying process; this can influence how the pylorus adapts over time. The combination of larger feedings and the responsive adaptation of the pylorus to manage those feedings is why hypertrophy is seen in this scenario.

This mechanism is distinct from other factors that might affect feeding patterns or growth differently, such as the content of protein or the frequency of feedings, which do not directly correlate to the observed changes in the pylorus.