Table 2.

Adjusted ORs for the association between maternal age and smoking during the second and third trimesters of pregnancy across socioeconomic groups among nulliparous and multiparous women, from 2000 to 2015 in Finland

Socioeconomic status (SES)	Maternal age (years)
	<19	20–24	25–29	30–34	>35
Nulliparous
Self-employed persons	7.77 (7.41–8.14)*	3.40 (3.27–3.54)	1.29 (1.23–1.34)	1.00 (ref)	1.19 (1.12–1.26)
Upper-level employees	8.68 (8.28–9.10)	3.79 (3.65–3.95)	1.41 (1.35–1.47)	1.00 (ref)	0.97 (0.91–1.02)
Lower-level employees	6.55 (6.28–6.82)	2.94 (2.85–3.04)	1.20 (1.16–1.24)	1.00 (ref)	1.10 (1.06–1.15)
Manual worker	5.31 (5.11–5.52)	2.55 (2.47–2.62)	1.16 (1.12–1.19)	1.00 (ref)	1.27 (1.22–1.32)
Students	7.45 (7.14–7.78)	2.96 (2.86–3.07)	1.23 (1.18–1.27)	1.00 (ref)	1.43 (1.38–1.48)
Long-term unemployed	6.41 (6.13–6.69)	2.85 (2.78–2.92)	1.46 (1.43–1.49)	1.00 (ref)	1.19 (1.13–1.26)
SES unknown	5.75 (5.51–6.00)	2.66 (2.57–2.75)	1.15 (1.11–1.19)	1.00 (ref)	1.31 (1.26–1.38)
Multiparous
Self-employed persons	5.25 (4.98–5.54)	2.77 (2.71–2.84)	1.45 (1.42–1.48)	1.00 (ref)	0.99 (0.96–1.01)
Upper-level employees	5.30 (5.03–5.59)	2.81 (2.74–2.87)	1.44 (1.41–1.48)	1.00 (ref)	0.99 (0.96–1.01)
Lower-level employees	5.12 (4.88–5.37)	2.74 (2.68–2.80)	1.41 (1.38–1.44)	1.00 (ref)	1.00 (0.98–1.03)
Manual workers	4.80 (4.60–5.01)	2.66 (2.60–2.70)	1.42 (1.39–1.45)	1.00 (ref)	1.00 (0.97–1.02)
Students	5.26 (5.01–5.52)	2.77 (2.71–2.83)	1.40 (1.37–1.43)	1.00 (ref)	1.04 (1.01–1.07)
Long-term unemployed	5.40 (5.13–5.69)	2.83 (2.76–2.90)	1.46 (1.42–1.49)	1.00 (ref)	0.99 (0.96–1.01)
SES unknown	5.37 (5.11–5.64)	2.81 (2.74–2.87)	1.45 (1.42–1.48)	1.00 (ref)	0.99 (0.97–1.02)

For the association between maternal age and smoking across socioeconomic groups, women aged 30–34 years, used as the reference group (ref).

*Adjusted OR, 95% CI (adjusted by marital status).