Table 1:

Baseline characteristics of participants according to whether they received seasonal influenza vaccine during pregnancy

Characteristic	Missing data, no. (%)	Vaccination status; no. of women		Vaccination rate, %	p value^*
Characteristic	Missing data, no. (%)	No vaccine n = 10 265	Vaccine n = 1 958	Vaccination rate, %	p value^*
Age, yr	0				0.7
< 20		598	114	16.0
20–29		4 935	920	15.7
30–34		3 059	584	16.0
≥ 35		1 673	340	16.9
Body mass index	2 378 (19.5)				0.5
< 18.5 (underweight)		414	71	14.6
18.5–24.9 (normal)		3 964	812	17.0
25–29.9 (overweight)		1 900	384	16.8
≥ 30 (obese)		1 900	400	17.4
Marital status	645 (5.3)				0.003
Married or common law		6 947	1 421	17.0
Single, widowed or divorced		2 739	471	14.7
Education level	6 155 (50.4)				0.1
1–3 (high school or technical college)		1 920	498	20.6
4–7 (postsecondary or higher)		2 955	695	19.0
Location of residence	0				0.02
Urban		7 417	1 362	15.5
Rural		2 848	596	17.3
Neighbourhood income	986 (8.1)				0.03
Lowest quintile1,2		3 837	686	15.2
Highest quintile3–5		5 591	1 123	16.7
Smoking during pregnancy	92 (0.8)				< 0.001
No		7 951	1 607	16.8
Yes		2 228	345	13.4
Parity	0				0.01
0		4 706	959	16.9
≥ 1		5 559	999	15.2
Season of delivery	0				0.02
November 2010–March 2011		2 868	575	16.7
April–October 2011		4 532	796	14.9
November–March 2012		2 865	587	17.0
Maternal risk status^†	0				< 0.001
Low		8 037	1 460	15.4
High		2 228	498	18.3
Previous pregnancy loss	124 (1.0)				0.5
No		10 017	1 923	16.1
Yes (≥ 1)		137	22	13.8
≥ 1 child at home aged < 5 yr	0				0.7
No		6 318	1 213	16.1
Yes		3 947	745	15.9
Gestational diabetes	0				0.8
No		9 754	1 864	16.0
Yes		511	94	15.5
Gestational hypertension	0				0.1
No		10 110	1 938	16.1
Yes		155	20	11.4
Pre-existing hypertension	0				0.2
No		10 151	1 943	16.1
Yes		114	15	11.6
Any psychiatric condition	0				0.02
No		9 148	1 710	15.7
Yes		1 117	248	18.2
No. of fetuses	0				0.7
1		10 093	1 928	16.0
≥ 2		172	30	14.9
Sex of infant	0				0.7
Female		5 024	968	16.2
Male		5 241	990	15.9

↵* χ² test.
↵† Pre-existing diabetes, pulmonary disease (including asthma), renal disease, heart disease or anemia.