Table 2.

Four-year average SMM rates per 1000 births for neighbourhood material deprivation quintiles, by pooled sample (2002–2018) and by study period cohort

Cohort*	SMM rates by material deprivation quintile					Q5 versus Q1
	Q1 (least)	Q2	Q3	Q4	Q5 (most)	Rate difference (95% CI)	Rate ratio (95% CI)
Pooled	17.58	16.68	17.55	17.89	19.43	1.84 (1.82 to 1.87)***	1.10 (1.10 to 1.11)***
1	16.05	16.36	17.46	16.49	18.14	2.09 (0.62 to 3.56)**	1.13 (1.04 to 1.23)**
2	16.58	15.97	15.73	16.37	17.32	0.75 (−0.70 to 2.20)	1.05 (0.96 to 1.14)
3	19.36	16.17	18.34	19.19	20.78	1.41 (−0.20 to 3.02)	1.07 (0.99 to 1.16)
4	18.41	18.52	18.99	20.18	22.32	3.91 (2.12 to 5.70)***	1.21 (1.11 to 1.32)***

**p<0.01, ***p<0.001.

*Cohort 1: 1 April 2002 to 31 March 2006; cohort 2: 1 April 2006 to 31 March 2010; cohort 3: 1 April 2010 to 31 March 2014; cohort 4: 1 April 2014 to 31 March 2018.

SMM, severe maternal morbidity.