Table 2.
Characteristics of the biological mothers of the individuals included to the study by GAa category.
| Extremely preterm | Very preterm | Moderately preterm | Late preterm | Early term | Full term | Post Term | Total cohort | |
|---|---|---|---|---|---|---|---|---|
| 23–27 weeks | 28–31 weeks | 32–33 weeks | 34–36 weeks | 37–38 weeks | 39–41 weeks | 42 weeks | 23–42 weeks | |
| Mother married at the birth of the index child, n (%) | 166 (69.2) | 588 (69.7) | 830 (72.2) | 6244 (75.3) | 31,411 (79.0) | 129,839 (78.9) | 6672 (74.1) | 175,750 (78.5) |
| Mother smoked during pregnancy, n (%) | 52 (21.7) | 148 (17.5) | 237 (20.6) | 1515 (18.3) | 6239 (15.7) | 23,803 (14.5) | 1466 (16.3) | 33,460 (15.0) |
| Maternal pregnancy disorder during index pregnancy, n (%)b | 28 (11.7) | 204 (24.2) | 310 (27.0) | 1715 (20.7) | 6560 (16.5) | 12,964 (7.9) | 418 (4.6) | 22,199 (9.9) |
| Maternal data available from the CPR, n | 239 | 844 | 1149 | 8287 | 39,750 | 164,466 | 8996 | 223,731 |
| Maternal age; years, mean (SD) | 30.0 (5.5) | 29.0 (5.7) | 29.1 (5.9) | 28.8 (5.6) | 28.9 (5.4) | 28.4 (5.1) | 27.8 (4.9) | 28.5 (5.2) |
| Age | ||||||||
| Less than 20 years, n (%) | 4 (1.7) | 37 (4.4) | 49 (4.3) | 319 (3.8) | 1186 (3.0) | 4569 (2.8) | 322 (3.6) | 6486 (2.9) |
| 35 years or more, n (%) | 51 (21.3) | 160 (19.0) | 221 (19.2) | 1414 (17.1) | 6374 (16.0) | 20,640 (12.5) | 876 (9.7) | 29,736 (13.3) |
| Maternal educational level, highest ever attained, n (%) | ||||||||
| Basic only or unknown | 47 (19.6) | 130 (15.4) | 231 (20.1) | 1380 (16.7) | 5966 (15.0) | 21,172 (12.9) | 1202 (13.4) | 30,128 (13.5) |
| Upper-secondary, less than tertiary | 152 (63.3) | 569 (67.4) | 723 (62.9) | 5464 (65.9) | 26,175 (65.8) | 111,122 (67.6) | 6069 (67.4) | 150,274 (67.2) |
| Lower tertiary or more | 41 (17.1) | 145 (17.2) | 195 (17.0) | 1444 (17.4) | 7610 (19.1) | 32,180 (19.6) | 1727 (19.2) | 43,342 (19.4) |
The amount of missing data was 0.0% (n = 14) for maternal education, 0.4% (n = 997) for maternal marital status at childbirth, and 1.9% (n = 4253) for maternal smoking in pregnancy.
aGA—gestational age. Completed weeks of gestation.
bPregnancy disorder includes gestational diabetes, gestational hypertensive disorder, and intrahepatic cholestasis of pregnancy. A complete list of diagnose codes included in this variable is available from Supplementary Material and elsewhere42.