Characteristics of the 216 of 372 eligible children who were born extremely preterm* in Norway in 1999–2000 and participated in the follow-up at 11 years of age
| Family background | % (n) |
| Single parent | 8.8 (19) |
| Higher education mother† | 68.8 (148) |
| Higher education father† | 45.1 (96) |
| Demographic characteristics | Mean (range) |
| Gestational age, weeks | 26.6 (23.0–32.0) |
| Birth weight, grams | 869 (450–1370) |
| % (n) | |
| Small for gestational age‡ | 18.1 (39) |
| Boy | 51.4 (111) |
| Severe disability§ (based on clinical examination at 5 years) | 3.3 (6) |
| Current smoking, mother or father | 35.2 (76) |
*Gestational age <28 weeks or birth weight <1000 g.
†College or university education when the child was 11 years old.
‡Small for gestational age: birth weights <10th percentile.22
§Severe disability defined as one or more of the following: cerebral palsy class 4–5 on the Gross Motor Function Classification System for Cerebral Palsy, Full intelligence quotient (IQ) score more than 3SDs below the reference mean value of 100, legal blindness, or complete deafness.10