Table 6. Parental smoking in relation to risk of developing hepatoblastoma (all results adjusted for parental age and deprivation).

	Father preconception						Mother preconception						Mother 2nd trimester
	Cases	Controls	OR	95% CI			Cases	Controls	OR	95% CI			Cases	Controls	OR	95% CI
Total	27	6987	2.19	0.94	5.12		28	7581	2.68*	1.16	6.21		28	7581	1.10	0.43	2.41
Age of the index child
Age< median	13	823	1.28	0.37	4.41		14	897	0.71	0.18	2.84		14	896	0.92	0.49	2.89
⩾median	14	6164	3.27	0.94	11.33		14	6684	12.02**	2.54	56.75		14	6685	1.28	0.44	2.72
No. of cigarattes smoked per day
0	11	3082	1.00				10	3916	1.00				21	5743	1.00
1–19	6	1003	1.88	0.67	5.26		9	1490	2.99*	1.15	7.76		5	1306	1.09	0.39	3.04
20+	7	1440	1.65	0.61	4.45		4	882	2.17	0.65	7.20		2	528	1.12	0.25	4.99
Trend P						0.272						0.058						0.844
Ex-smoker	0	827					2	758	0.98	0.21	4.53
Parental smoking
Neither parent	8	3142	1.00
Mother only	2	574	2.02	0.40	10.20
Father only	3	1008	1.86	0.46	7.55
Both parents	10	1249	4.74**	1.68	13.35

^*P<0.05.

^**P<0.01.