Table 1.
Descriptive characteristics of the study population according to fetal growth in first offspring (n = 22,460).
| Fetal growth | |||
|---|---|---|---|
| SGAa (n = 3,085) | AGAb (n = 17,995) | LGAc (n = 1,380) | |
| Maternal characteristics | |||
| Birthyear, median (IQR) | 1957 (1950–1965) | 1959 (1952–1968) | 1961 (1953–1970) |
| Age at first birth, median (IQR) | 23 (20–26) | 23 (20–27) | 24 (21–27) |
| Height in cm, mean (SD) | 164.2 (5.8) | 166.3 (5.7) | 168.5 (5.8) |
| Ever daily smoking, n (%) | |||
| Yes | 2,096 (67.9) | 10,209 (56.7) | 720 (52.2) |
| No | 989 (32.1) | 7,786 (43.3) | 660 (47.8) |
| Education, n (%) | |||
| Lower secondary (≤9 years) | 667 (21.6) | 2,868 (15.9) | 221 (16.0) |
| Upper secondary (10–12 years) | 1,489 (48.3) | 8,500 (47.2) | 621 (45.0) |
| Tertiary (>12 years) | 929 (30.1) | 6,627 (36.8) | 538 (39.0) |
| Ever use of antihypertensive medication, n (%) | |||
| Yes | 454 (14.7) | 1,795 (10.0) | 144 (10.4) |
| No | 2,631 (85.3) | 16,196 (90.0) | 1,236 (89.6) |
| Missing | 0 (0) | 4 (0) | 0 (0) |
| Age at 1st HUNT exam, median (IQR) | 32 (27–38) | 31 (26–37) | 31 (26–36) |
| No. of HUNT exams, n (%) | |||
| 1 | 1,066 (34.6) | 7,125 (39.6) | 605 (43.8) |
| 2 | 978 (31.7) | 5,372 (29.9) | 379 (27.5) |
| 3 | 1,041 (33.7) | 5,498 (30.6) | 396 (28.7) |
| HUNT exams relative to first pregnancy, n (%) | |||
| Before first pregnancy only | 235 (7.6) | 1,660 (9.2) | 158 (11.5) |
| After first pregnancy only | 2,588 (83.9) | 14,526 (80.7) | 1,078 (78.1) |
| Before and after first pregnancy | 262 (8.5) | 1,809 (10.1) | 144 (10.4) |
| Achieved parity | |||
| 1 | 455 (14.8) | 2,231 (12.4) | 195 (14.1) |
| 2 | 1,401 (45.4) | 8,147 (45.3) | 610 (44.2) |
| 3 | 920 (29.8) | 5,762 (32.0) | 436 (31.6) |
| ≥4 | 309 (10.0) | 1,855 (10.3) | 139 (10.1) |
| First pregnancy characteristics | |||
| Pre-pregnancy diabetes, n (%) | 4 (0.1) | 38 (0.2) | 9 (0.6) |
| Gestational diabetes, n (%) | 1 (0.03) | 36 (0.2) | 9 (0.7) |
| Pre-pregnancy hypertension, n (%) | 13 (0.4) | 58 (0.3) | 5 (0.4) |
| Preeclampsia or gestational hypertension, n (%) | 345 (11.2) | 1,027 (5.7) | 96 (7.0) |
| Gestational length, n (%) | |||
| Preterm (<37 weeks) | 238 (7.7) | 868 (4.8) | 162 (11.7) |
| Term (37–41 weeks) | 2,374 (77.0) | 14,270 (79.3) | 963 (69.8) |
| Postterm (≥42 weeks) | 473 (15.3) | 2,857 (15.9) | 255 (18.5) |
| Birthweight in grams, mean (SD) | 2,715 (429) | 3,510 (439) | 4,306 (540) |
| Stillbirths, n (%) | 76 (2.5) | 86 (0.5) | 8 (0.6) |
SGA = small for gestational age; AGA = appropriate for gestational age; LGA = large for gestational age; IQR = interquartile range, SD = standard deviation. Percentages may not sum to 100% due to rounding.
aSGA was defined as birthweight below the 10th centile for the Norwegian population.
bAGA was defined as birthweight ≥10th and ≤90th centile for the Norwegian population.
cLGA was defined as birthweight above the 90th centile for the Norwegian population.