The increasing incidence of infantile hypertrophic pyloric stenosis.

Several reports have suggested that there is an increasing incidence of infantile hypertrophic pyloric stenosis (IHPS). We examined the incidence of IHPS in a stable population in the West of Ireland over a ten year period (1981-1990). During the 10 years of the study the number of live births per year did not alter significantly. The incidence of IHPS increased significantly from 0.87/1000 live births in 1981 to 5.10/1000 in 1990 (p < 0.001, Student's test), peaking in 1989 at 6.8/1000. There was no statistical correlation between the increasing incidence and feeding habits, birth rank, family history or gender distribution. The reason(s) for this increase remain unclear.