Matching characteristics
| Characteristics | Freestanding midwifery unit (%) | Obstetric unit (%) |
| Complete match retained in all cases | ||
| Obstetric risk status | ||
| Low risk | 839 (100) | 839 (100) |
| Parity | ||
| Primiparous | 215 (25.6) | 215 (25.6) |
| Multiparous | 624 (74.4) | 624 (74.4) |
| Smoking status | ||
| Non-smoker | 684 (81.5) | 684 (81.5) |
| 1–9 cigarettes | 59 (7.0) | 59 (7.0) |
| 10 or more cigarettes | 96 (11.5) | 96 (11.5) |
| Individuals matched within ranges/groups | ||
| BMI | ||
| <18 | 17 (2.1) | 22 (2.6) |
| 18–24.9 | 528 (62.9) | 530 (63.2) |
| 25–29.9 | 226 (26.9) | 219 (26.1) |
| >30 | 68 (8.1) | 68 (8.1) |
| Age | ||
| 16–20 | 24 (2.9) | 25 (3.0) |
| 21–35 | 731 (87.1) | 716 (85.3) |
| >35 | 84 (10.0) | 98 (11.7) |
| Ethnicity | ||
| Nordic or Western European | 805 (96.0) | 809 (96.4) |
| Eastern European or Asian | 27 (3.2) | 22 (2.6) |
| Arab or African | 7 (0.8) | 8 (1.0) |
| Education level* | ||
| No training/education qualifying for the labour market | 216 (25.7) | 217 (25.9) |
| Skilled training | 255 (30.4) | 255 (30.4) |
| 1–2½ years of postsecondary education | 84 (10.0) | 81 (9.6) |
| 3–4 years of postsecondary education | 254 (30.3) | 256 (30.5) |
| 5–6 years of postsecondary education | 30 (3.6) | 30 (3.6) |
| Occupation | ||
| No paid work | 160 (19.1) | 131 (15.6) |
| Unskilled work | 107 (12.7) | 119 (14.2) |
| Skilled work† | 542 (64.6) | 557 (66.4) |
| Academic work/manager or senior official | 30 (3.6) | 32 (3.8) |
| Cohabitation status | ||
| Living with partner | 815 (97.1) | 819 (97.6) |
| Not living with partner | 24 (2.9) | 20 (2.4) |