Perinatal outcome by socioeconomic group, Finland, 1991–1999 (n=565863)*
| Children | Total | Unadjusted OR§ | Adjusted OR, Model I¶ | Adjusted OR, Model II** | Explanation percentage for smoking | |
|---|---|---|---|---|---|---|
| *All differences between the socioeconomic groups are statistically significant, p<0.001. | ||||||
| †Gestational age less than 37 weeks, per delivery. | ||||||
| ‡Birth weight less than 2500 g. | ||||||
| §Crude odds ratio with 95% confidence intervals. Singletons only. | ||||||
| ¶OR with 95% confidence interval adjusted by maternal age, parity, and county of residence. Singletons only. | ||||||
| **OR with 95% confidence interval adjusted by maternal age, parity, county of residence, and smoking. Singletons only. | ||||||
| Number | 565863 | 548913 | 548913 | 548913 | ||
| Prematurity, %† | ||||||
| Upper white collar workers | I | 5.0 | 1.00 | 1.00 | 1.00 | |
| Lower white collar workers | II | 5.2 | 1.02 (0.99 to 1.06) | 1.11 (1.05 to 1.18) | 1.09 (1.06 to 1.13) | 18 |
| Blue collar workers | III | 5.5 | 1.09 (1.05 to 1.14) | 1.35 (1.25 to 1.45) | 1.20 (1.15 to 1.25) | 42 |
| Others | O | 5.1 | 0.98 (0.95 to 1.02) | 1.30 (1.20 to 1.40) | 1.23 (1.18 to 1.28) | 22 |
| Low birth weight, %‡ | ||||||
| Upper white collar workers | I | 4.0 | 1.00 | 1.00 | 1.00 | |
| Lower white collar workers | II | 4.2 | 1.03 (0.99 to 1.07) | 1.20 (1.10 to 1.27) | 1.11 (1.06 to 1.15) | 48 |
| Blue collar workers | III | 4.6 | 1.16 (1.11 to 1.22) | 1.42 (1.35 to 1.49) | 1.25 (1.19 to 1.31) | 41 |
| Others | O | 4.1 | 1.01 (0.97 to 1.06) | 1.41 (1.35 to 1.48) | 1.31 (1.24 to 1.37) | 26 |
| Small for gestational age, % | ||||||
| Upper white collar workers | I | 2.1 | 1.00 | 1.00 | 1.00 | |
| Lower white collar workers | II | 2.3 | 1.07 (1.01 to 1.13) | 1.20 (1.14 to 1.27) | 1.11 (1.05 to 1.17) | 46 |
| Blue collar workers | III | 2.8 | 1.30 (1.22 to 1.38) | 1.57 (1.48 to 1.67) | 1.28 (1.20 to 1.37) | 51 |
| Others | O | 2.3 | 1.04 (0.98 to 1.11) | 1.46 (1.37 to 1.55) | 1.29 (1.17 to 1.37) | 37 |
| Perinatal mortality, 1/1000 | ||||||
| Upper white collar workers | I | 5.6 | 1.00 | 1.00 | 1.00 | |
| Lower white collar workers | II | 6.2 | 1.10 (0.99 to 1.22) | 1.18 (1.06 to 1.31) | 1.15 (1.04 to 1.28) | 15 |
| Blue collar workers | III | 7.4 | 1.32 (1.18 to 1.49) | 1.50 (1.33 to 1.60) | 1.41 (1.25 to 1.59) | 18 |
| Others | O | 8.1 | 1.42 (1.27 to 1.58) | 1.49 (1.32 to 1.67) | 1.43 (1.27 to 1.62) | 11 |