Table 3.
Background characteristics of IVF mothers in the MBR and in the IVF research data, Finland 1996–1998, %1)
| MBR | IVF research data | p | |
| Deliveries | 3557 | 3594 | |
| Age at birth, years | 0.029 | ||
| Less than 25 years | 2.9 | 2,9 | |
| 25–29 | 19.0 | 17.3 | |
| 30–34 | 40.7 | 40.7 | |
| 35–39 | 29.4 | 29.4 | |
| 40 or more | 8.1 | 9.7 | |
| Mean age | 33.6 | 33.9 | 0.005 |
| SD | 4.5 | 4.5 | |
| Single mother | 3.8 | 2.9 | 0.024 |
| Number of previous pregnancies | 0.744 | ||
| 0 | 50.0 | 49.5 | |
| 1 | 26.1 | 26.3 | |
| 2 | 12.4 | 12.0 | |
| 3 or more | 11.5 | 12.2 | |
| Number of previous births | 0.299 | ||
| 0 | 70.8 | 72.0 | |
| 1 | 22.0 | 21.4 | |
| 2 | 5.1 | 4.3 | |
| 3 or more | 2.1 | 2.3 | |
| Smoked during pregnancy | 7.1 | 6.5 | 0.339 |
| Socioeconomic position | < 0.001 | ||
| Upper white-collar | 24.9 | 26.7 | |
| Lower white-collar | 48.7 | 49.6 | |
| Blue-collar | 13.3 | 14.9 | |
| Other2) | 13.1 | 8.8 | |
1) No information available in the IVF statistics. 2) Including entrepreneurs, farmers, students, unemployed, retired, housewives and others for whom no social class could be stated.