Demographic characteristics of preterm infants assessed at 2 years corrected age
| Characteristics | Number (%) or mean (SD) | ||
| Gestational age (GA) | |||
| GA <32 weeks (n=86) | GA ≥32 weeks (n=98) | Total (n=184) | |
| Boys, n (%) | 52 (60) | 65 (66) | 117 (64) |
| Birth weight (g), mean (SD) | 1377 (251) | 2085 (387) | 1754 (484) |
| Gestational age (week), mean (SD) | 29.4 (1.5) | 33.5 (1.4) | 31.6 (2.5) |
| GA distribution, n (%) | |||
| <28 weeks | 12 (14) | _ | 12 (7) |
| 28 weeks–<32 weeks | 74 (86) | _ | 74 (40) |
| 32 weeks–<34 weeks | _ | 53 (54) | 53 (29) |
| 34 weeks–<37 weeks | _ | 45 (46) | 45 (24) |
| Multiple births (all twins), n (%) | 12 (14) | 14 (14) | 26 (14) |
| Living in the city of study-site, n (%) | 13 (15) | 27 (28) | 40 (22) |
| Mother age at birth (years), mean (SD) | 28.6 (5.9) | 29.0 (6.2) | 28.8 (6.0) |
| Maternal education*, n (%) | |||
| Elementary school or less | 25 (29) | 33 (34) | 58 (32) |
| High school (junior or senior) | 52 (60) | 52 (53) | 104 (57) |
| College or higher level | 9 (10) | 13 (13) | 22 (12) |
| Maternal occupation, n (%) | |||
| Skilled job† | 16 (19) | 18 (18) | 34 (18) |
| Housewife | 28 (33) | 24 (24) | 52 (28) |
| Farmer | 12 (14) | 8 (8) | 20 (11) |
| Others‡ | 30 (35) | 48 (49) | 78 (42) |
| Primary care by parents§, n (%) | 78 (90) | 91 (93) | 169 (92) |
| Ethnic minority (non-Kinh)¶, n (%) | 1 (1) | 2 (2) | 3 (2) |
Of note, data on income status were not available due to indeterminate responses from parents’ perspective.
Because of rounding, percentages may not total 100.
↵*Educational system consists of the basic education and the higher education. Twelve-year basic education includes 5 years in elementary school, 4 years in junior high school and 3 years in senior high school. The higher education includes college, undergraduate and postgraduate education in the universities.
↵†Skilled job refers to professional and intellectual work.
↵‡Other jobs refer to unskilled labour and shopkeeper.
↵§Other primary caregivers were grandparents or other relatives.
↵¶Ethnic minority includes Khmer, Chinese.