Birth characteristics of all surviving extremely low birthweight (ELBW) infants, the subcohort (ELBW infants born and followed in Helsinki University Hospital), and their controls
| All surviving ELBW infants (208 infants, 193 mothers) | Subcohort (78 infants, 74 mothers) | Control group (75 infants, 75 mothers) | |
|---|---|---|---|
| Values are number (%) or mean (range). | |||
| *p<0.05 (subcohort v entire cohort). | |||
| †p<0.05 (subcohort v control group). | |||
| GW, Gestational weeks. | |||
| Basic data | |||
| Primiparity | 104 (54) | 42 (58)† | 26 (35) |
| Unmarried mother | 67 (37) | 31 (42)† | 16 (21) |
| Upper social classes 1–2 | 120 (65) | 47 (64)† | 62 (83) |
| Lower social classes 3–4 | 66 (36) | 27 (36)† | 13 (17) |
| Mother smoked | 37 (19) | 14 (19) | 9 (12) |
| Mother’s age (years) | 31.5 (16.3–48.5) | 32.5 (21.5–47.5) | 32.0 (21.3–43.9) |
| Birth weight (g) | 807 (447–995) | 778 (447–995)†* | 3671 (2530–5250) |
| Gestational age (weeks) | 27.3 (22.3–34.9) | 27.1 (23.7–32.6)† | 39.9 (37.3–42.1) |
| Male sex | 97 (47) | 38 (49) | 39 (52) |
| Multiple pregnancy | 55 (26) | 16 (21)† | 2 (3) |
| Antenatal steroid treatment | 164 (79) | 69 (88)†* | 0 |
| Born in tertiary hospital | 187 (90) | 78 (100) | 75 (100) |
| Vaginal delivery | 68 (33) | 23 (29)† | 58 (77) |
| Morbidity data | |||
| Small for gestational age | 84 (40) | 35 (45)† | 1 (1) |
| Intraventricular haemorrhage grades 2–4 | 24 (12) | 6 (8) | |
| Respiratory distress syndrome | 144 (69) | 54 (69) | |
| Septicaemia | 53 (26) | 30 (38)* | |
| Retinopathy of prematurity stage 3–5 | 19 (9) | 4 (5) | |
| Oxygen dependency at the age corresponding to 36 GW | 81 (39) | 31 (40) | |