Table 1. Participant Characteristics.
| Characteristic | Participants, No./total No. (%)a | P valueb | |
|---|---|---|---|
| Preterm (n = 170) | Term (n = 91) | ||
| Gestational age at birth, median (range), wk + d | 30 + 0 (22 + 1 to 32 + 6) | 39 + 4 (36 + 3 to 42 + 1) | <.001 |
| Gestational age at MRI, median (range), wk + d | 40 + 5 (36 + 2 to 45 + 6) | 42 + 0 (38 + 2 to 46 + 1) | <.001 |
| Birth weight, median (range), g | 1315 (370 to 2510) | 3460 (2410 to 4560) | <.001 |
| Birthweight z score, median (range) | 0.13 (−3.13 to 2.14) | 0.45 (−2.30 to 2.57) | <.001 |
| Head circumference, median (range), cmc | 27.5 (17.5 to 33.8) | 35 (32 to 39) | <.001 |
| Head circumference z score, median (range)c | −0.12 (−3.13 to 5.31) | 0.99 (−1.54 to 3.73) | <.001 |
| Sex | |||
| Male | 95/170 (55.9) | 50/91 (54.9) | .21 |
| Female | 75/170 (44.1) | 41/91 (45.1) | |
| Maternal smoking during pregnancy | 30/167 (18.0) | 3/91 (3.3) | <.001 |
| Multiple pregnancy | 51/170 (30.0) | 2/91 (2.2) | <.001 |
| Any breast milk at discharge | 122/167 (73.1) | 85/91 (93.4) | <.001 |
| Child ethnicity | |||
| Asian | 4/166 (2.4) | 3/86 (3.5) | .22 |
| Black | 2/166 (1.2) | 0/86 | |
| Mixed ethnicity | 9/166 (5.4) | 5/86 (5.8) | |
| White | 145/166 (87.3) | 76/86 (90.7) | |
| Other ethnic groupd | 5/166 (3.0) | 0/86 | |
| SIMD rank, median (range) | 3913 (6-6929) | 5502 (727-6967) | <.001 |
| Mother age leaving education, median (range), ye | 20 (14-33) | 23 (16-36) | <.001 |
| Father age leaving education, median (range), yf | 18 (14-34) | 22 (16-36) | <.001 |
| Mother highest educational qualification | |||
| None | 5/165 (3.0) | 0/91 | <.001 |
| Basic high school qualification | 18/165 (10.9) | 5/91 (5.5) | |
| Advanced high school qualification | 13/165 (7.9) | 2/91 (2.2) | |
| College qualification | 42/165 (25.5) | 9/91 (9.9) | |
| University undergraduate degree | 44/165 (26.7) | 40/91 (44.0) | |
| University postgraduate degree | 34/165 (20.6) | 35/91 (38.5) | |
| Not applicable | 9/165 (5.5) | 0/91 | |
| Father highest educational qualification | |||
| None | 4/148 (2.7) | 0/90 | <.001 |
| Basic high school qualification | 33/148 (22.3) | 7/90 (7.8) | |
| Advanced high school qualification | 13/148 (8.8) | 5/90 (5.6) | |
| College qualification | 33/148 (22.3) | 12/90 (13.3) | |
| University undergraduate degree | 33/148 (22.3) | 41/90 (45.6) | |
| University postgraduate degree | 22/148 (14.9) | 25/90 (27.8) | |
| Not applicable | 10/148 (6.8) | 0/90 | |
| Mother current or recent job | |||
| Professional | 75/166 (45.2) | 76/91 (83.5) | <.001 |
| Nonmanual skilled | 32/166 (19.3) | 6/91 (6.6) | |
| Manual skilled | 16/166 (9.6) | 1/91 (1.1) | |
| Partly skilled | 8/166 (4.8) | 4/91 (4.4) | |
| Unskilled | 14/166 (8.4) | 2/91 (2.2) | |
| Unemployed | 3/166 (1.8) | 1/91 (1.1) | |
| Homemaker | 10/166 (6.0) | 0/91 | |
| Still in full-time education | 7/166 (4.2) | 1/91 (1.1) | |
| Father current or recent job | |||
| Professional | 59/157 (37.6) | 63/91 (69.2) | <.001 |
| Nonmanual skilled | 23/157 (14.6) | 6/91 (6.6) | |
| Manual skilled | 37/157 (23.6) | 7/91 (7.7) | |
| Partly skilled | 22/157 (14.0) | 6/91 (6.6) | |
| Unskilled | 6/157 (3.8) | 3/91 (3.3) | |
| Unemployed | 3/157 (1.9) | 0/91 | |
| Homemaker | 3/157 (1.9) | 0/91 | |
| Still in full time education | 3/157 (1.9) | 6/91 (6.6) | |
| WHO QoL environment score, median (range) | 75.0 (21.9 to 100.0) | 84.4 (40.6 to 100.0) | <.001 |
Abbreviations: MRI, magnetic resonance imaging; SIMD, Scottish Index of Multiple Deprivation; WHO QoL, World Health Organization Quality of Life assessment.
a
Case definitions are available in eMethods in Supplement 1.
b
For binary data, the χ2 test was used for P values. For continuous data, Mann-Whitney U test was used.
c
For head circumference and head circumference z score, there were data for 157 preterm infants and 83 full-term infants.
d
This included Arab, Iraqi, Bulgarian/Turkish, and Fijian.
e
For maternal age leaving education, data were available for 158 preterm and 85 full-term infants.
f
For partner age leaving education, data were available for 139 preterm and 79 full-term infants.