Study population characteristics at index date, for all mothers at the birth of their first child
| N=228 555 (n (%)) | |
| Year of child birth | |
| 2000–2005 | 108 475 (47.5) |
| 2006–2016 | 120 080 (52.5) |
| Age (years) of mother | |
| ≤27 | 86 243 (37.7) |
| 28–31 | 69 295 (30.3) |
| 32–34 | 32 799 (14.4) |
| ≥35 | 40 218 (17.6) |
| District | |
| Center | 153 862 (67.3) |
| North | 39 139 (17.1) |
| South | 35 554 (15.6) |
| Socioeconomic status* | |
| 1–5 | 76 114 (33.3) |
| 6 | 47 279 (20.7) |
| 7–10 | 105 162 (46.0) |
| Smoking | |
| Never | 200 122 (87.6) |
| Ever | 20 488 (9.0) |
| Unknown | 7945 (3.5) |
| Comorbid conditions | |
| Cardiovascular | 2486 (1.1) |
| Diabetes mellitus | 1070 (0.5) |
| Hypertension | 2232 (1.0) |
| Cancer | 1507 (0.7) |
| Fertility register | 42 389 (18.5) |
*Scale between 1 (lowest) to 10.