Testing the association between psychosocial job strain and adverse birth outcomes - design and methods

BMC Public Health

Table 2 Cross-tabulation between exposure variable and covariates

Characteristics	High strain		Active		Passive		Low strain
N = 50485	N	%	N	%	N	%	N	%
	3442	6.8	11435	22.7	4427	8.8	31181	61.8
Maternal age
<25	318	9.2	656	5.7	494	11.2	1987	6.4
25-29	1320	38.4	4108	35.9	1751	39.6	12012	38.5
30-34	1341	39.0	4765	41.7	1575	35.6	12325	39.5
>35	463	13.5	1906	16.7	607	13.7	4857	15.6
Parity
0 births	1603	46.6	5668	49.6	2218	50.1	16193	51.9
1 birth	1256	36.5	4150	36.3	1557	35.2	10518	33.7
≥ 2 births	580	16.9	1605	14.0	648	14.6	4456	14.3
Smoking during pregnancy
No	2346	68.2	8529	74.6	3171	71.6	24331	78.0
Less than daily	442	12.8	1314	11.5	501	11.3	3168	10.2
Daily	654	19.0	1590	13.9	754	17.0	3669	11.8
*Alcohol (units per week)**
0	2009	58.4	6123	53.6	2458	55.5	16506	52.9
<1	516	15.0	1787	15.6	742	16.8	5145	16.5
1-2	764	22.2	2962	25.9	1067	24.1	8122	26.1
>2	147	4.3	546	4.8	155	3.5	1381	4.4
Coffee
0 cups per day	1873	54.4	6116	53.5	2527	57.1	17295	55.5
>0 cups per day	1568	45.6	53.18	46.5	1998	42.9	13877	44.5
Physical exercise
None	2312	67.2	7047	61.6	2934	66.3	18606	59.7
<3.5 hours per week	898	26.1	3541	31.0	1227	27.7	10277	33.0
≥ 3.5 hours per week	221	6.4	820	7.2	255	5.8	2233	7.2
BMI
15-18.4	126	3.7	460	4.0	194	4.4	1224	3.9
18.5-24.9	2262	65.7	7943	69.5	2857	64.5	21336	68.4
25-29.9	707	20.5	2054	18.0	927	20.9	5902	18.9
30-50	294	8.5	786	6.9	378	8.5	2193	7.0
Type of work
Manual	2093	60.8	5389	47.1	2045	46.2	11856	38.0
Non-manual	1349	39.2	6041	52.8	2378	53.7	19307	61.9
Maternal diabetes or epilepsy
Neither	3377	98.1	11238	98.3	4342	98.1	30751	98.6
either or both	62	1.8	183	1.6	80	1.8	391	1.3
Gestational age at interview (weeks)
<16	1802	52.4	5756	50.3	2363	53.4	16060	51.5
16 - 21	1640	47.7	5679	49.7	2064	46.6	15121	48.5

* one unit is equal 12 grams of alcohol which corresponds to one normal beer (33 centilitre), one glass of wine (12,5 centilitre) or 4 centilitre spirits.

ISSN: 1471-2458