Table 1.

History of whooping cough by sex, year of birth and region of birth

	ALSPAC				1958 Birth Cohort
	Overall	Cases	Controls	P-value	Overall	Cases	Controls	P-value
Sex
Male	—	—	—	—	0.49 (2499)	0.14 (342)	0.86 (2157)	0.013
Female	1 (7156)	0.11 (815)	0.89 (6341)		0.51 (2567)	0.16 (416)	0.84 (2151)
Total	1 (7156)	0.11 (815)	0.89 (6341)		1 (5066)	0.15 (758)	0.85 (4308)
Year of birth
1948–1952	0.02 (112)	0.28 (31)	0.72 (81)	<0.001		—	—	—
1953–1957	0.11 (773)	0.18 (138)	0.82 (635)			—	—
1958–1962	0.32 (2303)	0.11 (250)	0.89 (2053)		1 (5066)	0.15 (758)	0.85 (4308)
1963–1967	0.4 (2831)	0.09 (258)	0.91 (2573)			—	—
1968–1972	0.14 (977)	0.11 (112)	0.89 (865)			—	—
1973–1976	0.02 (160)	0.16 (26)	0.84 (134)			—	—
Total	1 (7156)	0.11 (815)	0.89 (6341)		1 (5066)	0.15 (758)	0.85 (4308)

The proportions (counts) of participants within those designated as ‘cases’ and ‘controls’ and overall are shown within strata with a P-value for a chi-square test of association where possible. The symbol ‘—’ indicates no data. A u-shaped association with year of birth was confirmed by second-order polynomial regression (P = 2E − 10 for addition of the squared term).