Air pollution in the week prior to delivery and preterm birth in 24 Canadian cities: a time to event analysis

Table 3 Pooled hazard ratios, 95% confidence intervals and heterogeneity measures from distributed lag models

Lag	Hazard Ratio^a	95% confidence interval^a		p	I²	Q	p(Q)
0	1.032	1.017	1.048	<.0001	12.83%	26.3845	0.2831
1	1.010	1.001	1.020	0.0327	26.81%	31.4232	0.1127
2	0.994	0.984	1.005	0.2897	38.81%	37.5859	0.0282
3	0.985	0.973	0.997	0.0171	33.68%	34.6821	0.0559
4	0.987	0.978	0.996	0.0066	23.55%	30.0833	0.147
5	1.000	0.993	1.007	0.9832	0.00%	18.9691	0.703
6	1.019	1.006	1.032	0.005	0.00%	22.7601	0.4749
0–1	1.032	1.016	1.049	<.0001	16.81%	27.649	0.2293
0–2	1.042	1.016	1.068	0.0012	23.37%	30.0158	0.1489
0–3	1.036	1.005	1.067	0.0209	29.10%	32.4378	0.0914
0–4	1.022	0.987	1.057	0.227	33.94%	34.8155	0.0543
0–5	1.009	0.971	1.049	0.6396	34.61%	35.1717	0.05
0–6	1.006	0.971	1.042	0.7587	20.63%	28.9787	0.181

ISSN: 1476-069X