| FTC | PTC | RDS | CLD | |
| Total No (% male) | 64 (44) | 59 (42) | 54 (57) | 42 (57) |
| HUH No (% male) | 25 (40) | 22 (50) | 7 (42) | 17 (47) |
| UCLH No (% male) | 4 (25) | 10 (50) | 5 (60) | 7 (71) |
| KEMH No (% male) | 35 (48) | 27 (33) | 42 (60) | 18 (61) |
| Gestation (weeks) | 39.7 (1.2) | 33.5 (1.9) | 29.6 (2.3)† | 26.6 (2.1)‡,§ |
| Birth weight (kg) | 3.36 (0.41) | 1.85 (0.50) | 1.32 (0.45)† | 0.89 (0.29)‡,§ |
| Birth weight z score22 | −0.12 (0.90) | −0.78 (1.19) | −0.34 (1.18) | −0.58 (0.29) |
| Ethnicity (% Caucasian) | 73 | 70 | 85 | 64§ |
| In utero smoke exposure (%) | 13 | 22 | 21 | 12 |
| Antenatal steroids (%) | – | 62 | 87† | 86‡ |
| PROM (%) | – | 19 | 15 | 26 |
| Surfactant | – | – | 83 | 95 |
| Total respiratory support (days)*¶ | – | 0.0 (0.0; 0.0) | 4.8 (1.3; 21)† | 42 (16; 70)‡,§ |
| Total invasive ventilation (days)* | – | – | 0.6 (0.2; 1.0) | 4.8 (0.6; 39)§ |
| O2 requirement (days)* | – | 0.0 (0.0; 0.0) | 1.5 (0.0; 16) | 88 (75; 156)‡,§ |
Results expressed mean (SD) if not stated otherwise. Invasive ventilation indicates tracheal tube in place.
*Median (interquartile range). †Significant difference between PTC and RDS. ‡Significant difference between PTC and CLD. §Significant difference between RDS and CLD (see online supplement for details). ¶Total respiratory support (days): total number of days the child received either invasive (ie, intubated) or non-invasive (continuous positive airway pressure) ventilatory support.
CLD, Chronic Lung Disease; FTC, full term controls; HUH, Homerton University Hospital; KEMH, King Edward Memorial Hospital; PROM, prolonged rupture of membranes; PTC, preterm controls; RDS, respiratory distress syndrome; UCLH, University College London Hospital.