Table 1

Multivariate analysis of risk factors for SIDS

Risk factor	Cases		Controls		Stage 1		Stage 2		Stage 3		Stage 4		Stage 5		Stage 6		Stage 7		Stage 8		Stage 9
Risk factor	%	n	%	n	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
p<0.05; *p<0.01. †Odds ratio significant at p<0.01 but figure difficult to estimate due to the small sample size and large combination of variables included at this stage. Mean Z score −0.43 (cases), 0.13 (controls).
Sociodemographic variables
Social Deprivation Index (3–5)	54.1	85	12.3	76	5.91**	3.36–10.46	5.26**	2.92–9.45	3.52**	1.87–6.63	2.76**	1.35–5.66	4.13**	1.74–9.82	3.69*	1.36–9.97	3.59*	1.21–10.42	2.42	0.61–9.51	1.53	0.28–14.41
Mother’s age (<25 y)	33.5	61	10.8	67	1.51	0.79–2.89	1.60	0.84–3.08	1.57	0.77–3.21	1.18	0.51–2.74	0.68	0.24–1.90	2.10	0.58–7.65	1.86	0.45–7.62	3.53	0.34–35.95	1.04	0.04–25.55
Mother’s education (less than 3rd level)	85.0	163	74.9	438	1.63	0.91–2.93	1.52	0.84–2.75	1.65	0.83–3.26	1.53	0.67–3.46	1.23	0.50–3.16	1.57	0.53–4.61	1.64	0.54–4.96	0.89	0.16–4.70	1.20	0.15–9.10
Marital status (single, separated, widowed)	43.3	77	12.1	75	1.97*	1.02–3.80	2.06*	1.25–4.50	1.68	0.78–3.64	1.78	0.71–4.51	1.86	0.56–6.16	1.10	0.29–3.89	1.36	0.35–5.30	1.84	0.24–14.44	7.72	0.31–186.80
Pregnancy history
Live births (3+)	21.0	38	11.3	70			2.38**	1.25–4.50	1.81	0.88–3.74	1.37	0.73–3.79	1.44	0.56–3.67	1.56	0.55–4.38	1.89	0.64–5.55	2.73	0.55–13.72	32.82*	1.31–819.97
During pregnancy
Mother smoking <10 cigs/day	30.7	51	16.8	104					2.82**	1.55–5.15	2.25*	1.10–4.61	1.91	0.84–4.32	2.65*	1.00–6.97	2.04	0.75–5.56	2.64	0.59–11.71	2.07	0.30–14.41
Mother smoking 10+ cigs/day	42.8	71	10.3	64					3.92**	2.01–7.66	3.07**	1.36–6.90	3.81**	1.42–10.25	7.06**	2.20–22.61	4.57*	1.33–15.66	3.53	0.70–17.85	1.32	0.19–8.85
Mother drinking (any quantity)	63.5	101	50.0	311					1.77*	1.07–2.94	1.62	0.91–2.88	1.86	0.93–3.73	1.98	0.93–4.23	1.85	0.84–4.07	1.79	0.59–5.38	2.32	0.50–10.79
UTI (self report)	23.3	38	6.0	37					3.22**	1.53–6.78	4.12**	1.76–9.70	6.39**	2.14–19.08	9.94**	2.74–35.98	8.04**	2.06–31.28	12.61*	1.58–100.40	27.47*	1.12–673.85
Birth issues
Mode of delivery (other than normal vaginal)	76.5	143	69.7	400							1.46	0.70–3.05	2.39	0.99–5.78	1.50	0.55–4.04	1.7	0.59–4.85	2.31	0.42–12.61	11.09	0.68–179.53
z scores for weight by gestation											0.74	0.53–1.04	0.69	0.46–1.04	0.68	0.42–1.09	0.60	0.35–1.00	0.61	0.27–1.41	0.21*	0.05–0.98
Resuscitation (any)	35.5	66	23.9	136							1.36	0.67–2.73	1.14	0.50–2.56	0.91	0.35–2.32	0.84	0.31–2.25	1.09	0.28–4.22	2.18	4.00–11.91
Sex of baby (male)	60.6	123	49.0	305							1.40	0.77–2.53	1.53	0.74–3.20	2.05	0.87–4.80	1.92	0.76–4.92	1.49	0.38–5.88	3.02	0.30–29.87
Special care unit	20.2	38	9.0	51							1.77	0.70–4.43	1.75	0.55–5.49	1.73	0.45–6.56	1.69	0.40–7.12	1.83	0.24–14.20	4.84	0.27–84.95
Breast feeding initiated	23.1	37	46.2	287							0.85	0.42–1.70	0.85	0.37–1.86	1.01	0.39–2.62	0.69	0.24–1.98	1.18	0.25–5.41	1.31	0.17–10.17
After birth
Baby being ill (any illness)	64.3	101	27.3	169									5.38**	2.39–12.12	5.96**	2.35–15.11	6.03**	2.22–16.28	5.50*	1.50–20.64	21.23**	2.16–208.86
Baby prone to sweating	35.3	55	15.6	97									3.87**	1.44–10.44	4.66**	1.46–14.85	5.81**	1.70–19.77	4.83	0.83–28.10	7.96	0.77–82.90
Regurgitation	28.0	44	18.9	117									2.85*	1.07–7.57	2.93	0.95–8.99	3.01	0.93–9.75	3.49	0.65–18.67	6.01	0.58–61.92
Feeding problems	26.5	41	18.4	114									0.58	0.21–1.59	0.47	0.15–1.47	0.53	0.16–1.74	0.93	0.19–4.44	0.78	0.11–5.51
Crying/colic problems	37.6	59	22.4	139									3.12**	1.36–7.12	3.83**	1.51–9.70	3.33*	1.27–8.71	2.90	0.75–10.83	5.01	0.80–31.47
Last week
Visit to GP	34.8	54	21.0	130											1.82	0.59–5.52	1.34	0.38–4.64	2.10	0.41–10.71	7.53	0.68–82.37
On medication (prescribed or not)	25.3	37	16.2	91											0.55	0.17–1.76	0.60	0.18–2.03	0.62	0.12–3.03	0.14	0.01–1.72
Last 48 hours
Ill in the last 48 hours (any illness)	41.9	65	26.3	163													2.18	0.82–5.76	3.34	0.85–13.10	8.05	0.96–67.31
Baby sleeping more than usual	18.7	21	9.0	56													2.04	0.59–7.00	3.23	0.55–18.70	5.89	0.41–83.31
Baby had an unusual cry	16.0	25	4.2	26													1.98	0.42–9.35	1.51	0.13–16.79	5.70	0.20–160.92
Baby drowsy when awake	10.9	17	2.3	620													0.48	0.10–2.25	0.24	0.02–2.08	0.05	0.00–1.18
Baby taking less fluids than norm	15.5	24	7.3	45													0.55	0.04–7.56	2.40	0.11–51.74	24.70	0.39–1522.32
Last sleep period
Co-sleeping	43.9	68	5.0	32															41.41**	3.55–483.68	† **	†
Use of pillows	44.4	68	11.8	73															0.98	0.17–5.54	1.99	0.20–20.19
Tog count of coverings (10+)	66.9	101	50.0	310															1.29	0.37–4.40	0.98	0.20–4.95
Use of duvets	53.3	81	19.0	118															0.68	0.15–3.04	0.86	0.14–5.30
Lack of routine soother use	46.7	70	19.4	119															4.49**	1.47–13.71	10.60**	1.83–61.49
Position placed to sleep (prone)	12.3	19	2.4	15																	† **	†