Table 1. Study background characteristics of the ESTER birth cohort (births in Northern Finland during 1985–89): Clinical Examination during 2009–11.
| Variable | Subgroup | Early Preterm <34 weeks | Late preterm 34-<37 weeks | Full-term ≥37weeks | Missing (n) |
|---|---|---|---|---|---|
| n = 139 | n = 239 | n = 341 | Early pretem/Late Preterm /Term | ||
| mean (SD)/n (%) | mean (SD)/n (%) | mean (SD)/n (%) | |||
| Maternal smoking during pregnancy a | 23 (16.5%) | 46 (19.2%) | 54 (15.8%) | 0/0/0 | |
| Highest parental education a | Secondary or less or unknown | 97 (69.8%) | 159 (66.5%) | 229 (67.2%) | 0/0/0 |
| Lower tertiary | 13 (9.4%) | 30 (12.6%) | 44 (12.9%) | ||
| Upper tertiary | 29 (20.9%) | 50 (20.9%) | 68 (19.9%) | ||
| Maternal body mass index before pregnancy b | 22.5 (3.5) | 22.7 (4.0) | 22.3 (3.0) | 8/7/13 | |
| Antenatal glucocorticoid treatmentc | 20 (22.2%) | 7 (6.5%) | 0 (0%) | 0/0/0 | |
| Maternal gestational diabetesd | 4 (2.9%) | 11 (4.6%) | 6 (1.8%) | 0/0/0 | |
| Hypertensive disorder during pregnancy† | Normotensivea | 85 (63.0%) | 167 (72.3%) | 274 (84.3%) | 4/8/16 |
| Gestational hypertensiona | 7 (5.2%) | 20 (8.7%) | 27 (8.3%) | ||
| Preeclampsiaa† | 23 (17.0%) | 22 (9.5%) | 8 (2.5%) | ||
| Chronic hypertension** | 12 (8.9%) | 16 (6.9%) | 9 (2.8%) | ||
| Superimposed preeclampsia* | 8 (5.9%) | 6 (2.6%) | 7 (2.2%) | ||
| Mean length of gestation (weeks)b† | 31.8 (1.9) | 35.8 (0.8) | 40.1 (1.2) | 0/0/0 | |
| Maternal age at birthb | 29.4 (5.4) | 29.4 (6.0) | 28.1 (5.5) | 0/0/0 | |
| Multiple pregnancy (twins)d | 33 (23.7%) | 32 (13.4%) | 4 (1.2%) | 0/0/0 | |
| Source cohorta,e† | NFBC | 49 (35.3%) | 131 (54.8%) | 205 (60.1%) | 0/0/0 |
| FMBR | 90 (64.7%) | 108 (45.2%) | 136 (39.9%) | 0/0/0 | |
| Sexa | Male | 66 (47.5%) | 118 (49.4%) | 164 (48.1%) | 0/0/0 |
| Female | 73 (52.5%) | 121 (50.6%) | 177 (51.9%) | ||
| Birth weight (g)b† | 1777 (482) | 2670 (521) | 3583 (485) | 0/0/0 | |
| Birth weight SD scoreb† | -0.72 (1.40) | -0.64 (1.29) | -0.00 (1.00) | 0/0/0 | |
| SGA (birth weight<-2SD)a† | 22 (15.8%) | 30 (12.6%) | 6 (1.8%) | 0/0/0 | |
| Bronchopulmonary dysplasiaf | 12 (8.6%) | 1 (0.4%) | 0 (0%) | 0/0/0 | |
| Respirator care | Not treated in respirator | 72 (51.8%) | 210 (87.9%) | 339 (99.4%) | 0/0/0 |
| <7 days | 51 (36.7%) | 26 (10.9%) | 2 (0.6%) | ||
| 7 to <14 days | 9 (6.5%) | 3 (1.3%) | 0 (0%) | ||
| 14 or more days | 7 (5.0%) | 0 (0%) | 0 (0%) | ||
| Age at clinical examination (y)b† | 23.1 (1.4) | 23.2 (1.2) | 23.5 (1.1) | 0/0/0 | |
| Height (cm) | womenb | 162.5 (6.2) | 164.5 (5.7) | 164.0 (5.8) | 0/0/0 |
| menb | 178.2 (7.5) | 177.7 (6.7) | 177.8 (6.9) | 0/0/0 | |
| BMI (kg/m2)g | womenb | 24.3 (5.8) | 23.7 (4.3) | 23.3 (4.3) | 0/0/0 |
| menb | 24.2 (4.0) | 25.3 (4.7) | 24.3 (4.3) | 0/0/0 | |
| Obesity (BMI: 30≥kg/m2) | womenb | 12 (16.4%) | 9 (7.4%) | 17 (9.6%) | 0/0/0 |
| menb | 8 (12.1%) | 18 (15.2%) | 8 (4.9%) | 0/0/0 | |
| Pregnant (currently)h,d | 5 (6.8%) | 3 (2.5%) | 7 (3.9%) | 0/0/0 | |
| Volume of self-reported leisure-time physical activity (METh/week)b | 23.3 (13.5) | 24.7 (14.5) | 25.9 (14.2) | 3/5/7 | |
*p-value <0.05
**p-value <0.01
†p-value <0.001
aChi-square
bOneway ANOVA F-value
c Data available for participants from Finnish Medical Birth Register (FMBR), participants born 1987–1989
d Fisher’s exact test
eSource cohort: FMBR, Finnish Medical Birth Register, participants born 1987–1989; NFBC, Northern Finland Birth Cohort, participants born 1985–1986
fDefinition based on pediatrician’s diagnoses (for NFBC), and the receipt of supplementary oxygen at 28 days of age (for FMBR) [24].
gBMI, body mass index
hOf women only