Table 1.

Characteristics of acute myeloid leukemia (AML) cases and controls by study design and age at diagnosis (<1 year, 1-14 years)

Age at diagnosis
	<1 year								1-14 years
Study design →	Registry-based CCa (no of studies=7)				Questionaire-based CC (no of studies =10)				Registry-based CC (no of studies =7)				Questionaire-based CC (no of studies =10)
	AML cases N=285		Controls N=922		AML cases N=186		Controls N=402		AML cases N=1603		Controls N=5180		AML cases N=1108		Controls N=1873
Variables ↓	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%
Index child’s age at diagnosis/recruitment (years)
<1	285	100.0	922	100.0	186	100.0	402	100.0
1-4									766	47.8	2468	47.7	456	41.2	814	43.5
5-9									389	24.3	1260	24.3	331	29.9	579	30.9
10-14									448	27.9	1452	28.0	321	28.9	480	25.6
Index child’s sex
Male	131	46.0	423	45.9	100	53.8	243	60.5	836	52.2	2719	52.5	595	53.7	977	52.2
Female	154	54.0	499	54.1	86	46.2	159	39.5	767	47.8	2461	47.5	513	46.3	896	47.8
Time period at diagnosis/recruitment
1968-1993	96	33.7	297	32.2	67	36.0	110	27.4	493	30.8	1551	29.9	508	45.9	785	41.9
1994-2003	122	42.8	400	43.4	62	33.3	216	53.7	725	45.1	2356	45.5	390	35.2	821	43.8
2004-2015	67	23.5	225	24.4	57	30.7	76	18.9	387	24.1	1273	24.6	210	18.9	267	14.3
Index child’s race
Caucasian	181	63.5	576	62.6	149	80.1	266	66.2	1072	67.0	3395	65.6	823	74.4	1367	73.0
Non-Caucasian	104	36.5	344	37.4	37	19.9	136	33.8	529	33.0	1779	34.4	283	25.6	505	27.0
Missing	0	0.0	2	0.2	0	0.0	0	0.0	2	0.1	6	0.1	2	0.2	1	0.1
Birthweight (g)
<2500	23	8.2	48	5.3	7	3.8	43	10.9	93	6.0	264	5.2	55	5.1	126	6.9
2500-2999	44	15.8	133	14.6	32	17.5	89	22.5	234	15.1	742	14.7	182	16.7	316	17.3
3000-3499	102	36.5	323	35.5	60	32.8	131	33.1	514	33.2	1784	35.5	368	33.8	670	36.6
3500-3999	78	28.0	287	31.6	66	36.1	105	26.5	489	31.6	1567	31.2	336	30.8	533	29.1
≥4000	32	11.5	118	13.0	18	9.8	28	7.0	219	14.1	673	13.4	148	13.6	184	10.1
Missing	6	2.1	13	1.4	3	1.6	6	1.5	54	3.4	150	2.9	19	1.7	44	2.4
Maternal educationb
Low	42	17.4	118	14.6	42	22.8	130	32.4	170	15.5	503	14.2	294	26.8	520	28.1
Intermediate	131	54.4	462	57.1	97	52.7	210	52.4	655	59.6	2121	59.6	589	53.8	933	50.4
High	68	28.2	229	28.3	45	24.5	61	15.2	274	24.9	933	26.2	212	19.4	398	21.5
Missing	44	15.4	113	12.3	2	1.1	1	0.3	504	31.4	1623	31.3	13	1.2	22	1.2
Maternal smoking during pregnancy
No	156	92.9	536	95.0	150	81.1	297	74.2	721	92.7	2373	92.3	856	77.9	1437	77.1
Yes	12	7.1	28	5.0	35	18.9	103	25.8	57	7.3	199	7.7	243	22.1	428	22.9
Missing	117	41.1	358	38.8	1	0.5	2	0.5	825	51.5	2608	50.3	9	0.8	8	0.4
Preterm birthc
No	223	86.1	772	91.6	135	91.8	208	92.9	1287	89.0	4318	91.6	908	94.1	1440	92.9
Yes	36	13.9	71	8.4	12	8.2	16	7.1	159	11.0	394	8.4	57	5.9	110	7.1
Missing	26	9.1	79	8.6	39	21.0	178	44.3	157	9.8	468	9.0	143	12.9	323	17.3
Multiple pregnancy
No	266	97.4	865	97.6	176	96.7	385	97.5	1460	98.1	4709	97.4	1046	98.9	1695	97.7
Yes	7	2.6	21	2.4	6	3.3	10	2.5	28	1.9	124	2.6	12	1.1	39	2.3
Missing	12	4.2	36	3.9	4	2.2	7	1.7	115	7.2	347	6.7	50	4.5	139	7.4
Birth order
1	111	39.2	370	40.3	81	44.2	174	46.6	599	38.0	2065	40.4	491	45.2	777	44.9
2	82	29.0	315	34.3	64	35.0	107	28.7	528	33.4	1705	33.3	356	32.8	584	33.8
≥3	90	31.8	233	25.4	38	20.8	92	24.7	451	28.6	1343	26.3	239	22.0	368	21.3
Missing	2	0.7	4	0.4	3	1.6	29	7.2	25	1.6	67	1.3	22	2.0	144	7.7
Maternal age at birth (years)
<20	30	10.5	62	6.7	15	8.1	51	12.8	139	8.6	431	8.3	110	10.0	170	9.2
20-24	57	20.1	196	21.3	38	20.6	99	24.8	375	23.4	1267	24.5	285	25.9	449	24.2
25-29	73	25.7	307	33.3	59	31.9	134	33.6	503	31.4	1640	31.7	373	33.9	613	33.0
30-34	69	24.3	229	24.8	47	25.4	78	19.5	365	22.8	1229	23.7	237	21.5	435	23.4
35-39	36	12.7	109	11.8	20	10.8	31	7.8	179	11.2	507	9.8	84	7.6	162	8.7
≥40	19	6.7	19	2.1	6	3.2	6	1.5	42	2.6	106	2.0	12	1.1	27	1.5
Missing	1	0.4	0	0	1	0.5	3	0.8	0	0.0	0	0.0	7	0.6	17	0.9
Mean ± SD	28.5±6.79		28.1±5.66		27.9±6.09		26.4±5.84		27.6±5.99		27.4±5.73		26.8±5.53		27.2±5.66
Paternal age at birth (years)
<20	9	3.3	25	2.8	7	3.9	14	3.7	44	2.9	163	3.2	40	3.9	34	2.0
20-24	43	15.8	131	14.3	26	14.4	75	19.6	250	16.2	896	17.5	169	16.2	303	17.4
25-29	69	25.4	255	27.9	45	25.0	110	28.7	452	29.4	1512	29.5	321	30.8	503	28.9
30-34	72	26.5	256	28.0	50	27.8	103	26.9	415	27.0	1407	27.5	276	26.5	495	28.5
35-39	40	14.7	160	17.5	33	18.3	53	13.8	246	16.0	763	14.9	165	15.8	257	14.8
≥40	39	14.3	87	9.5	19	10.6	28	7.3	131	8.5	379	7.4	71	6.8	147	8.4
Missing	13	4.6	8	0.9	6	3.2	19	4.7	65	4.1	60	1.2	66	6.0	134	7.2
Mean ± SD	31.3±7.40		30.8±6.67		31.0±7.55		29.8±6.57		30.3±6.55		30.1±6.52		30.0±6.70		30.4±6.55

^aCC: Case control;

^bMaternal education: Low: secondary education not completed; intermediate: secondary education completed; high: college, university or higher degree;

^cPreterm birth: Yes: gestational age <37 weeks; No: gestational age ≥37 weeks