Maternal smoking during pregnancy increases the risk of recurrent wheezing during the first years of life (BAMSE)

Respiratory Research

Table 1 Characteristics of a cohort of children and their families by exposure to maternal daily smoking of one cigarette or more during pregnancy

	No foetal exposure			Foetal exposure to tobacco smoking
	n/N¹	%	95% CI	n/N¹	%	95% CI	p-value²
Gender (male)	1676/3321	51	49 – 52	242/469	52	47 – 56	0.646
Parental asthma	533/3302	16	15 – 17	73/457	16	13 – 19	0.927
Birth weight <2500 g	121/3321	3.6	3.0 – 4.3	19/469	4.1	2.5 – 6.3	0.661
Gestational age <36 w	102/3321	3.1	2.5 – 3.7	15/469	3.2	1.8 – 5.2	0.946
Exclusive breastfeeding ≥4 months	2690/3316	81	80 – 82	323/469	69	65 – 73	<0.001
Maternal age ≥26 years	3091/3320	93	92 – 94	413/469	88	85 – 95	<0.001
Socioeconomic index (SEI)³
1) Blue-collar	482/3311	15	13 – 16	140/468	30	26 – 34	<0.001
2) White collar	2792/3311	84	83 – 86	323/468	69	62 – 71	<0.001
3) Others⁴	37/3311	1.1	0.8 – 1.5	5/468	1.1	0.1 – 2.0	0.924
Keeping of cat and/or dog	426/3321	13	12 – 14	121/469	26	22 – 30	<0.001
Signs of dampness⁵	267/3309	8.1	7.1 – 9.0	39/468	8.3	5.8 – 11	0.844
Construction year of the home >1961	1679/3319	49	48 – 51	266/468	57	52 – 61	0.003

¹ The numbers do not add up because of missing data.
² Pearson chi-square test.
³ Socioeconomic status of the parents according to socioeconomic index measured by the Nordic standard occupational classification (NYK) and Swedish socioeconomic classification (SEI).
⁴ Student, unemployed etc.
⁵Smell or visible signs of mould in the dwelling and/or water damage inside construction.

ISSN: 1465-993X