Table 2

Selected sociodemographic and prenatal characteristics of the study population of the pooled analysis

Characteristics	ALL (11 studies)				AML (10 studies)
	Cases		Controls		Cases		Controls
	n	%	n	%	n	%	n	%
Child’s characteristics
Sex
Boy	4699	55.8	9097	55.3	483	52.2	6834	55.8
Girl	3721	44.2	7356	44.7	443	47.8	5412	44.2
Age at diagnosis/index date (years)*
<1	264	3.1	938	5.7	120	13.0	792	6.5
1–4	4515	53.6	8024	48.8	302	32.6	5741	46.9
5–9	2421	28.8	4689	28.5	228	24.6	3469	28.3
10–14	1220	14.5	2802	17.0	274	29.6	2235	18.3
Missing	0	0	0	0	2	0.2	9	0.1
Year of birth
≤1980	446	5.5	879	5.3	59	6.4	524	4.3
1981–1990	3770	44.8	7030	42.7	329	35.5	4748	38.8
1991–2000	3258	38.7	6572	39.9	401	43.3	5553	45.3
>2000	946	11.2	1972	12.0	137	14.8	1421	11.6
Case accrual time period†
1988–1992	2934	34.8	4856	29.5	159	17.2	2465	20.1
1993–1997	2181	25.9	5199	31.6	345	37.3	4660	38.1
1998–2002	1611	19.1	2910	17.7	180	19.4	2422	19.8
2003–2007	1291	15.3	2754	16.7	185	20.0	2292	18.7
2008–2013	403	4.8	734	4.5	57	6.2	407	3.3
Parental characteristics
Highest level of education‡
Did not finish secondary education	1352	16.1	2455	14.9	189	20.4	2394	19.5
Completed secondary education	3701	44.0	6914	42.0	363	39.2	4681	38.2
Tertiary education	3186	37.8	6528	39.7	346	37.4	4968	40.6
Missing	181	2.1	556	3.4	28	3.0	203	1.7
Maternal job history available
Yes	7864	93.4	15 884	96.5	902	97.4	12 005	98.0
No	556	6.6	569	3.5	24	2.6	241	2.0
Paternal job history available
Yes	7842	93.1	15 301	93.0	855	92.3	11 281	92.1
No	578	6.9	1152	7.0	71	7.7	965	7.9
Histological subtype
ALL B-lineage	5845		13 815
ALL T-lineage	781		13 815
Total	8420		16 453		926		12 246

*Child’s age at the index date: for cases, the date of diagnosis, and for controls, either the date of recruitment or the date of questionnaire return.
†Date of interview or questionnaire return for the control.
‡Based on the highest attained education level by the parents (either mother or father).
ALL, acute lymphoblastic leukaemia; AML, acute myeloid leukaemia.