Table 1. Comparison of the incidence and male-to-female rate of pyloric stenosis at different times and in different parts of the world.

Year studied	Authors	Area	No. of Cases	Incidence per 1000 live births	M/F rate	Trend
1968-1982	Lammer et al.	Atlanta, USA	518	1.332.90 (White, M)0.61 (Black, M)0.68 (White, F)0.17 (Black, F)	4.44∶1	NA
1971–1984	Hitchcock et al.	Western Australia	602	1.4–2.9	4.9∶1	Increasing
1974–1980	Knox et al.	Central Scotland, UK	1176	2.1–3.5	3.1–4.4∶1	Increasing
1976–19781986–1988	Tam et al.	Mersey, UK		1.542.22	3.55∶18.35∶1	Increasing
1981–2004	Sommerfield et al.	Scotland, UK	4950	4.4–1.4	NA	Declining
1983–1988	Schechter et al.	California, USA	1963	1.92.4 White1.8 Hispanic,0.7 Black0.6 Asian
1983–1990	Applegate et al.	New York, USA	2304	2.4–1.7	4.31∶1	Declining
1987–1996	Hedback et al.	Sweden	2157	2.7–0.85	4.15∶1	Declining
1993–19961997–2000	To et al.	Ontario, North America	1918	1.81–1.481.55–1.98	4∶1	DecliningIncreasing
1999–2002	Wang et al.	Texas, USA	2747	2.14 White2.49 Hispanic-US1.58 Hispanic-F0.83 Blacks0.18 Chinese0.44 Vietnamese0.59 Asian Indians0.43Filipinos
1997–2007	Leong et al.(current study)	Taiwan	1077	0.39	4.3∶1	Declining

F indicates female, M indicates male, NA indicates not available, UK indicates United Kingdom, USA indicates United States America, Hispanic-US indicates US-born Hispanic, Hispanic-F indicates foreign-born Hispanic.