Table 2. Distribution of missing values in final study population in crude numbers (%).
| First born n (%) |
Multiple birth n (%) |
Cesarean section n (%) |
Maternal educational level n (%) |
Maternal smoking n (%) |
||
|---|---|---|---|---|---|---|
| Total | 4906 (0.3) | 21 (0.0) | 2614 (0.1) | 14,029 (0.8) | 638,050 (35.1) | |
| By birth year group | 1980–1984 | 0 (0.0) | 1 (0.0) | 1845 (0.8) | 3098 (1.3) | 243,465 (100) |
| 1985–1989 | 1 (0.0) | 4 (0.0) | 433 (0.2) | 3073 (1.1) | 281,384 (100) | |
| 1990–1994 | 0 (0.0) | 2 (0.0) | 127 (0.0) | 2567 (0.8) | 80,499 (24.8) | |
| 1995–1999 | 562 (0.2) | 13 (0.0) | 91 (0.0) | 1882 (0.6) | 16,881 (5.1) | |
| 2000–2004 | 609 (0.2) | 1 (0.0) | 109 (0.0) | 1044 (0.3) | 8466 (2.6) | |
| 2005–2009 | 3734 (1.2) | 0 (0.0) | 9 (0.0) | 2365 (0.7) | 7355 (2.3) | |
| By gestational age group | 37+ | 4325 (0.3) | 14 (0.0) | 2419 (0.1) | 13,253 (0.8) | 605,081 (35.2) |
| 32–36 | 478 (0.5) | 4 (0.0) | 156 (0.1) | 696 (0.8) | 28,697 (32.1) | |
| 28–31 | 87 (0.8) | 0 (0.0) | 33 (0.3) | 68 (0.6) | 3558 (33.5) | |
| 23–27 | 16 (0.7) | 3 (0.1) | 6 (0.3) | 12 (0.5) | 714 (30.0) | |