Table 1.
Characteristics of the sample by exposure status
| Extremely to very preterm | Moderate to late preterm | Term | Post-term | Very Post-term | |
|---|---|---|---|---|---|
| Gestational weeks | 21–31 | 32–36 | 37–41 | 42 | 43–45 |
| Number of observations | 2601 | 20,271 | 438,215 | 34,828 | 3706 |
| Percentage of the cohort | 0.5 | 4.1 | 87.7 | 7.0 | 0.7 |
| % | % | % | % | % | |
| Female child | 45.2 | 46.3 | 49.3 | 44.1 | 43.9 |
| Mother’s number of prior pregnancies | |||||
| 0 | 53.4 | 53.4 | 44.2 | 53.8 | 61.5 |
| 1 | 27.1 | 28.4 | 37.0 | 30.1 | 23.5 |
| 2 | 12.5 | 11.8 | 13.6 | 11.6 | 10.0 |
| 3 + | 7.0 | 6.4 | 5.3 | 4.5 | 5.0 |
| Birth weight in grams | |||||
| < 2500 | 99.7 | 37.6 | 1.1 | 0.1 | 0.1 |
| 2500–4500 | 0.4 | 62.5 | 98.6 | 98.5 | 98.0 |
| > 4500 | 0.0 | 0.0 | 0.3 | 1.4 | 1.9 |
| Gestational hypertension or preeclampsia | 23.6 | 12.9 | 3.2 | 1.9 | 1.5 |
| Gestational diabetes | 1.5 | 1.7 | 0.8 | 0.4 | 0.4 |
| Delivery by Caesarean Section | 58.9 | 32.4 | 13.3 | 16.5 | 22.5 |
| Delivery assisted with ventouse or forceps | 1.4 | 4.7 | 8.0 | 14.1 | 14.9 |
| Maternal psychiatric history | 38.6 | 37.0 | 32.7 | 31.5 | 33.0 |
| Paternal psychiatric history | 23.7 | 22.6 | 20.9 | 20.4 | 21.2 |
| Family disposable income quintile at birth | |||||
| Lowest | 14.3 | 15.1 | 14.7 | 13.3 | 15.4 |
| Second | 21.7 | 20.4 | 20.8 | 19.4 | 19.1 |
| Third | 19.9 | 20.4 | 21.6 | 21.1 | 19.3 |
| Fourth | 22.3 | 22.3 | 21.6 | 22.6 | 22.1 |
| Highest | 21.8 | 21.8 | 21.4 | 23.6 | 24.2 |
| Parental educational attainment at birth | |||||
| ≤ 9 years | 9.0 | 8.0 | 6.5 | 5.8 | 7.0 |
| 10–11 years | 42.0 | 43.3 | 40.5 | 39.9 | 40.7 |
| ≥ 13 years | 49.0 | 48.7 | 53.0 | 54.2 | 52.3 |
| Maternal age | |||||
| ≤ 20 | 1.8 | 2.6 | 1.8 | 1.6 | 1.9 |
| 20–24 | 13.0 | 15.7 | 14.7 | 13.4 | 16.3 |
| 25–29 | 26.6 | 30.3 | 31.0 | 31.3 | 32.0 |
| 30–34 | 32.1 | 31.1 | 33.8 | 34.9 | 31.8 |
| 35–39 | 21.4 | 16.4 | 15.7 | 16.0 | 15.1 |
| 40 + | 5.2 | 4.0 | 3.2 | 2.8 | 2.9 |
| Paternal age | |||||
| ≤ 20 | 0.7 | 0.8 | 0.5 | 0.5 | 0.4 |
| 20–24 | 7.2 | 8.9 | 7.2 | 7.0 | 8.2 |
| 25–29 | 20.8 | 24.2 | 23.5 | 23.5 | 25.0 |
| 30–34 | 30.8 | 31.5 | 33.5 | 33.7 | 32.5 |
| 35–39 | 22.8 | 20.4 | 22.0 | 22.0 | 21.4 |
| 40 + | 17.7 | 14.2 | 13.3 | 13.3 | 12.6 |
| Maternal country of birth | |||||
| Sweden | 72.2 | 75.2 | 76.0 | 78.5 | 78.5 |
| Other Nordic | 5.1 | 4.6 | 4.2 | 4.2 | 4.6 |
| Other European | 4.3 | 3.6 | 3.6 | 3.5 | 3.3 |
| Baltic States /Russia | 0.6 | 0.5 | 0.5 | 0.7 | 0.5 |
| Africa | 5.3 | 3.1 | 3.4 | 4.9 | 5.5 |
| Middle East | 7.3 | 6.7 | 7.0 | 4.8 | 4.5 |
| Asia /Oceania | 3.2 | 3.7 | 2.8 | 1.7 | 1.7 |
| North America | 0.5 | 0.6 | 0.6 | 0.6 | 0.4 |
| South America | 1.5 | 2.0 | 1.9 | 1.3 | 1.1 |
| Paternal country of birth | |||||
| Sweden | 70.7 | 74.7 | 74.7 | 77.3 | 77.6 |
| Other Nordic | 4.3 | 3.5 | 3.2 | 3.0 | 3.4 |
| Other European | 4.6 | 4.5 | 4.7 | 4.6 | 4.5 |
| Baltic States /Russia | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
| Africa | 6.2 | 4.1 | 4.1 | 5.7 | 5.8 |
| Middle East | 8.6 | 7.6 | 8.3 | 5.8 | 5.5 |
| Asia/Oceania | 2.4 | 2.3 | 1.9 | 1.2 | 1.1 |
| North America | 0.8 | 0.7 | 0.8 | 0.7 | 0.70 |
| South America | 2.3 | 2.3 | 2.2 | 1.5 | 1.21 |
| Intellectual disability | 5.6 | 1.8 | 0.9 | 1.0 | 1.6 |