Table 2.

Univariate analysis of potential determinants of low birth weight by Indigenous status.

	Indigenous Infants, n=25544						Non-Indigenous Infants, n=16366
	2500 g+	<2500 g					2500 g+	<2500 g
	n	n	%	RR	(95% CI)	p	n	n	%	RR	(95% CI)	p
Infants	22363	3181	12.5				15414	952	5.8
Maternal Corrections History
Prison (before pregnancy)b	2235	574	20.4	2.20	(2.01–2.41)	<.001	549	92	14.4	3.23	(2.63–3.97)	<.001
Prison (during pregnancy)	622	157	20.2	2.17	(1.87–2.52)	<.001	216	29	11.8	2.66	(1.87–3.79)	<.001
Prison (after birth)	3024	539	15.1	1.63	(1.48–1.79)	<.001	2287	238	9.4	2.12	(1.83–2.46)	<.001
Community corrections	4984	732	12.8	1.38	(1.26–1.50)	<.001	596	46	7.2	1.61	(1.21–2.16)	.001
No corrections record*	11498	1179	9.3				11766	547	4.4
Demographic Factors
Sexc
Female	10708	1682	13.6	1.19	(1.12–1.27)	<.001	7376	488	6.2	1.14	(1.01–1.29)	.040
Male*	11578	1488	11.4				7994	461	5.5
Maternal Indigenous status
Indigenous	21259	3090	12.7	1.67	(1.36–2.04)	<.001
Non-Indigenous*	1104	91	7.6				15414	952	5.8
Socioeconomic statusd
Very low (0–5%)	5934	971	14.1	1.58	(1.37–1.81)	<.001	899	100	10.0	2.25	(1.81–2.80)	<.001
Low (6–25%)	9667	1400	12.7	1.42	(1.24–1.62)	<.001	4086	314	7.1	1.61	(1.38–1.88)	<.001
Medium (26–50%)	4447	582	11.6	1.30	(1.12–1.50)	<.001	4187	248	5.6	1.26	(1.07–1.49)	.006
High (51–100%)*	2296	225	8.9				6197	288	4.4
Geographical remotenesse
Cities/Inner regional*	8948	1354	13.1				12557	795	6.0
Outer regional	3792	518	12.0	0.91	(0.83–1.01)	.064	1689	111	6.2	1.04	(0.85–1.26)	.721
Remote	4237	487	10.3	0.78	(0.71–0.86)	<.001	797	30	3.6	0.61	(0.43–0.87)	.007
Very remote	5366	819	13.2	1.01	(0.93–1.09)	.856	314	13	4.0	0.67	(0.39–1.14)	.140
Baseline Pregnancy Risk Factors
Birth spacing
<18months	2581	444	14.7	1.21	(1.10–1.33)	<.001	992	97	8.9	1.59	(1.30–1.95)	<.001
Firstborn/18months+*	19782	2737	12.2				14422	855	5.6
Maternal age
12–19 years	6694	942	12.3	0.98	(0.90–1.07)	.634	1623	124	7.1	1.35	(1.11–1.63)	.002
20–24 years	8335	1144	12.1	0.96	(0.88–1.04)	.303	3687	250	6.4	1.21	(1.04–1.40)	.013
25–34 years*	6546	943	12.6				8390	466	5.3
35+years	788	152	16.2	1.28	(1.10–1.50)	.002	1714	112	6.1	1.17	(0.95–1.42)	.133
Parity
Nulliparous	7888	1181	13.0	1.10	(1.02–1.19)	.010	7382	477	6.1	1.14	(1.00–1.29)	.054
Parity 1–2*	9574	1283	11.8				7032	397	5.3
Parity 3+	4901	717	12.8	1.08	(0.99–1.18)	.078	1000	78	7.2	1.35	(1.07–1.71)	.011
Previous abortion
Yes	4428	675	13.2	1.08	(1.00–1.17)	.060	3049	234	7.1	1.30	(1.13–1.50)	<.001
No*	17935	2506	12.3				12365	718	5.5
Pregnancy Complications
Hypertension, preeclampsia or eclampsia
Yes	972	299	23.5	1.98	(1.78–2.20)	<.001	732	96	11.6	2.10	(1.72–2.57)	<.001
No*	21391	2882	11.9				14682	856	5.5
Any placental disorder
Yes	126	72	36.4	2.96	(2.46–3.57)	<.001	144	40	21.7	3.86	(2.91–5.11)	<.001
No*	22237	3109	12.3				15270	912	5.6
Premature rupture of membranes
Yes	805	390	32.6	2.85	(2.61–3.11)	<.001	345	82	19.2	3.52	(2.87–4.32)	<.001
No*	21558	2791	11.5				15069	870	5.5
Renal disorders in pregnancy
Yes	28	12	30.0	2.41	(1.50–3.88)	<.001	13	<5	13.3	2.29	(0.63–8.35)	.280
No*	22335	3169	12.4				15401	950	5.8
Infection related hospitalization
Yes	1,759	285	13.9	1.13	(1.01–1.27)	.032	351	31	8.1	1.41	(1.00–1.99)	.051
No*	20604	2896	12.3				15063	921	5.8
Other Maternal Factors/Exposures in Pregnancy
Substance use related service contactf
Yes	309	94	23.3	1.90	(1.59–2.27)	<.001	238	52	17.9	3.20	(2.48–4.13)	<.001
No*	22054	3087	12.3				15176	900	5.6
Hospitalisation for external causes of injuryg
Yes	1,143	338	22.8	1.93	(1.75–2.13)	<.001	250	29	10.4	1.81	(1.28–2.57)	.001
No*	21220	2843	11.8				15164	923	5.7
Mental health related service contacth
Yes	626	141	18.4	1.50	(1.29–1.75)	<.001	371	52	12.3	2.18	(1.68–2.83)	<.001
No*	21737	3040	12.3				15043	900	5.6
Sibling in contact with Child Protection
Yes	689	166	19.4	1.59	(1.38–1.83)	<.001	202	34	14.4	2.53	(1.84–3.48)	<.001
Firstborn/No*	21674	3015	12.2				15212	918	5.7

^*Reference category

^bPrison before, not during, pregnancy

^c88 Indigenous and 47 non-Indigenous infants missing sex.

^d22 Indigenous and 47 non-Indigenous infants missing socioeconomic status.

^e23 Indigenous and 60 non-Indigenous infants missing remoteness.

^fIncludes substance use and other (MHIS or HMDC).

^gIncludes assault, excludes poisoning (HMDC).

^hExcludes substance use related contacts (MHIS or HMDC).