Table 4: Frequency of perinatal outcomes at the time of birth of all Aboriginal mothers by smoking status during pregnancy and the estimated relative risk (RR) with 95% confidence intervals (95% CI).

*adjusted for maternal age, any hypertension, any diabetes, parity and socio-economic status (SEIFA).

Study population	N	%	RR (95% CI)
						Unadjusted	Adjusted*
Preterm birth
1	16,306	11.2
Smokers	8,109	14.2	0.58	0.58
Non-smokers	8,197	8.1	(0.53, 0.64)	(0.53, 0.64)
2	17,175	11.1
Smokers	8,467	14.2	0.58	0.59
Non-smokers	8,708	8.1	(0.53, 0.64)	(0.53, 0.64)
3	18,154	11.3
Smokers	8,919	14.4	0.59	0.58
Non-smokers	9,235	8.2	(0.54, 0.64)	(0.53, 0.64)
4	24,107	10.3
Smokers	10,646	13.6	0.58	0.58
Non-smokers	13,461	7.7	(0.54, 0.63)	(0.54, 0.63)
Small-for-gestational age (<10th percentile)
1	16,306	13.3
Smokers	8,109	19.7	0.36	0.35
Non-smokers	8,197	7.0	(0.33, 0.39)	(0.32, 0.38)
2	17,175	13.2
Smokers	8,467	19.6	0.36	0.35
Non-smokers	8,708	7.0	(0.33, 0.39)	(0.32, 0.38)
3	18,154	13.1
Smokers	8,919	19.5	0.36	0.35
Non-smokers	9,235	7.0	(0.33, 0.39)	(0.32, 0.39)
4	24,107	12.5
Smokers	10,646	19.3	0.37	0.36
Non-smokers	13,461	7.1	(0.35, 0.40)	(0.33, 0.39)
Perinatal death
1	16,306	1.4
Smokers	8,109	1.8	0.53	0.57
Non-smokers	8,197	1.0	(0.40, 0.70)	(0.42, 0.75)
2	17,175	1.4
Smokers	8,467	1.8	0.55	0.58
Non-smokers	8,708	1.0	(0.42, 0.71)	(0.44, 0.77)
3	18,154	1.4
Smokers	8,919	1.8	0.54	0.58
Non-smokers	9,235	1.0	(0.42, 0.70)	(0.44, 0.76)
4	24,107	1.3
Smokers	10,646	1.7	0.54	0.57
Non-smokers	13,461	0.9	(0.43, 0.68)	(0.45, 0.73)