Table 1.
Baseline characteristics for 3307 mothers at the time of 4212 pregnancies
| Unexposed (reference) | Exposed | |
|---|---|---|
| n pregnancies (%) | 3327 (79) | 885 (21) |
| Maternal age (SD) | 27.9 (5.4) | 27.5 (5.4) |
| Maternal ethncity | ||
| Nordic contries % | 64 | 68 |
| Non-nordic contries % | 36 | 32 |
| Missing % | 0 | 0 |
| Maternal level of education | ||
| Low % | 35 | 30 |
| Middle % | 27 | 26 |
| High % | 17 | 15 |
| Missing % | 21 | 29 |
| Calendar time of conception | ||
| 1970–1979% | 11 | 16 |
| 1980–1989% | 27 | 29 |
| 1990–1999% | 27 | 26 |
| 2000–2009% | 21 | 19 |
| 2010–2018% | 14 | 10 |
| Maternal smoking up to pregnancya | ||
| No % | 69 | 68 |
| Yes % | 23 | 22 |
| Missing % | 8 | 10 |
SD standard deviation
aAvailable since 1991 (unexposed n = 2028 and exposed n = 476)