Table 2. Mutually adjusted relative risks for the association between predictor variables and brain tumour risk.

Variable	Categories	Odds ratio (95% CI)	P-value
Sexa	Male	1.68 (1.21, 2.33)	0.003
	Female	1.0 (ref)
Maternal age (years)a	<25	0.70 (0.44, 1.12)
	25–34	1.0 (ref)	0.86
	⩾35	0.79 (0.45, 1.40)
Paternal agea	<25	1.49 (0.89, 2.50)
	25–34	1.0 (ref)	0.35
	⩾35	1.43 (0.90, 2.29)
Social classa	Non-manual	1.19 (0.82, 1.75)
	Manual/other	1.0 (ref)
Miscarriage historya	None	1.0 (ref)
	⩾1	1.64 (1.13, 2.40)	0.01
Gestation age (weeks)a	<38	0.70 (0.34, 1.42)
	38–39	1.0 (ref)	0.36
	⩾40	1.03 (0.73, 1.44)
Presumptive birth ordera	First born	1.0 (ref)
	Not first born	0.90 (0.60, 1.34)
Breast feda	Yes	1.0 (ref)
	No	1.09 (0.71, 1.66)
Birth weight (g)a	<2500	0.63 (0.30–1.312)	0.26
	2500–4000	1.0 (ref)
	>4000	1.27 (0.84, 1.92)
Number of children in household <15 yearsb,c	<3	1.0 (ref)
	⩾3	2.20 (1.12, 4.32)	0.02
Number of adults in householdc	<3	1.0 (ref)
	⩾3	2.93 (1.33, 6.49)	0.008
Household densityc	<1 person per room	1.0 (ref)
	⩾1 person per room	1.01 (0.40, 2.55)

^aThe analyses are based on 124 cases (80%) and 332 650 non-cases (79.1%) who had information available for all variables except number of children and adults in household and household density. Adjusted for year of birth (categorical) sex, maternal age, paternal age, social class, miscarriage history, gestation age, birth order, breastfed, and birth weight as appropriate.

^bIncludes the newborn.

^cThe analyses are based on 52 cases (33.5%) and 145 364 non-cases (34.6) who had information available on all variables. Adjusted for year of birth, sex, maternal age, paternal age, social class, miscarriage history, gestation age, birth order, breastfed, birth weight, number of children in household, numbers adults in household, and household density as appropriate.