TABLE 1

Characteristics of the study population at the age of 1 year, in 1998 (n=4101)

	n	%
Demographic factors
Ethnicity: South Asian	801	20
White	3300	80
Sex: boys	2135	52
Girls	1966	48
Family history^#
Asthma	1294	32
Bronchitis	739	18
Hay fever	1846	45
Eczema	1339	33
Indoor exposures
Day care	1030	25
Older siblings	2276	56
Cooking with gas	3051	74
Mother smoking	895	22
Father smoking	1041	25
Any pets	1664	41
Socioeconomic factors
Low maternal education^¶	1956	48
Deprived (Townsend score ≥1.86)⁺	1303	32
Perinatal and early life data
Preterm (gestational age <37 weeks)	281	7
Low birth weight (<2500 g)	293	7
Young mother (<25 years)^§	929	23
Child breastfed	2432	59
Reflux (posseting) in infancy	3061	75
Respiratory problems in the past year
Any night cough	938	23
Any wheeze	1420	35
Isolated night cough	427	10
Cough triggered by: exercise	408	10
aeroallergens	77	2
laughter^ƒ	727	22
food	427	10
Rhinitis	1291	32
Eczema^ƒ	1155	36
Frequent colds (>6 episodes)	777	19
Snoring	2236	55
Otitis	1706	42

^#: Either mother or father with a history of the disease; ^¶: age at the end of education of mother is ≤16 years; ⁺: Townsend deprivation index (deprived, the highest two quintiles): deprived (1.86, 5.15), more deprived (5.16, 11.07); ^§: when the child was born; ^ƒ: asked only in part of the cohort. Hay fever was not inquired about in the 1998 survey.