Table 1 Description of the study population: maternal characteristics.

	Children of women who smoked (n = 71)		Children of women who did not smoke (n = 71)
	n	%	n	%	χ2	df	p
Note: POS = general polytechnic secondary school certificate (school-leaving certificate of the GDR, corresponds to intermediate school leaving certificate), t = t-value, df = degrees of freedom, p = two-tailed significance test
Maternal educational level					0.795	2	0.672
no qualifications/certificate of secondary education	29	40.8	26	36.6
intermediate school-leaving certificate/POS	31	43.7	30	42.3
entrance qualification for advanced technical college or university	11	15.5	15	21,1
Marital status					5.358	1	0.021
single parent	24	33.8	12	16.9
Monthly family income (in Euros)					15.097	3	0.002
< 1 000	11	16.2	8	12.3
1 000–2 500	41	60.3	21	32.3
2 500–5 000	15	22.1	31	47.7
> 5 000	1	1.5	5	7.7
Marital status X income					17.957	3	0.000