Factors associated with infantile hypertrophic pyloric stenosis.

We examined perinatal factors in relation to the rise in incidence of infantile hypertrophic pyloric stenosis among children in Olmsted County, Minnesota, during the period from 1950 through 1984. Primogeniture was associated with male infants but not female infants; some factor related to primogeniture, such as breast-feeding, may be etiologically important. Our data did not support a role for maternal disease, use of doxylamine succinate-pyridoxide hydrochloride (Bendectin), or an infectious process. Further study should be directed toward environmental factors associated with primogeniture.