Infant characteristics according to gestational age at birth and stratified according to application of less invasive surfactant administration (LISA) versus a strategy of providing surfactant if needed after primary endotracheal intubation (n=1173)
| Gestational age | 22–24 weeks | 25–27 weeks | ||||||||||||
| 22 weeks* | 23 weeks | 24 weeks | 25 weeks | 26 weeks | 27 weeks | 25–27 weeks | P value† | |||||||
| LISA | No | Yes | No | Yes | No | Yes | No | Yes | No | Yes | No | Yes | No | |
| Number born (% LISA) | 14 (100) | 3 (2) | 128 (98) | 10 (5) | 176 (95) | 43 (20) | 169 (80) | 89 (30) | 210 (70) | 90 (27) | 242 (73) | 222 (26) | 621 (74) | |
| Antenatal steroids, n (%) | 10 (71%) | 3 (100%) | 111/127 (87%) | 10 (100%) | 164 (93%) | 43 (100%) | 158 (93%) | 86 (97%) | 185 (88%) | 80 (89%) | 217 (90%) | 209 (94%) | 560 (90%) | 0.07 |
| Caesarean section, n (%) | 4 (29%) | 1 (33%) | 12 (9%) | 5 (50%) | 49 (28%) | 20 (47%) | 89 (53%) | 41 (46%) | 99 (47%) | 43 (48%) | 127 (52%) | 104 (47%) | 315 (51%) | 0.32 |
| Girls, n (%) | 4 (29%) | 1 (33%) | 57 (45%) | 7 (70%) | 78 (44%) | 25 (58%) | 81 (48%) | 35 (39%) | 87 (41%) | 42 (47%) | 110 (45%) | 102 (46%) | 278 (45%) | 0.76 |
| Birth weight, g, mean (SD) | 518 (60) | 513 (88) | 558 (68) | 706 (69) | 655 (89) | 785 (124) | 737 (148) | 830 (151) | 844 (179) | 967 (164) | 972 (200) | 877 (169) | 865 (204) | 0.39 |
| SGA‡, n (%) | 2 (14%) | 1 (33%) | 25 (20%) | 0 (0%) | 32 (18%) | 4 (9%) | 34 (20%) | 26 (29%) | 54 (26%) | 22 (24%) | 58 (24%) | 52 (23%) | 146 (24%) | 0.98 |
| Apgar 1 min, mean (SD) | 3.4 (2.5) | 4.0 (3.0) | 3.9 (2.0) | 5.1 (1.9) | 4.1 (2.1) | 5.5 (1.8) | 4.4 (2.2) | 5.8 (2.0) | 4.6 (2.4) | 5.8 (2.0) | 5.6 (2.4) | 5.7 (2.0) | 4.9 (2.4) | <0.001 |
| Apgar 5 min, mean (SD) | 4.6 (1.9) | 4.0 (1.7) | 5.6 (2.1) | 7.3 (1.2) | 5.9 (2.1) | 7.3 (1.5) | 6.3 (1.9) | 7.7 (1.5) | 6.4 (2.2) | 7.6 (1.6) | 7.1 (2.1) | 7.6 (1.5) | 6.6 (2.1) | <0.001 |
| Surfactant, n (%) | 13 (93%) | 3 (100%) | 118 (92%) | 10 (100%) | 166 (94%) | 43 (100%) | 149 (88%) | 89 (100%) | 155 (74%) | 90 (100%) | 137 (57%) | 222 (100%) | 441 (71%) | <0.001 |
| CRIB II, mean (SD) | 17.1 (1.3) | 16.0 (2.0) | 16.0 (1.4) | 14.7 (1.4) | 14.5 (1.5) | 12.1 (1.3) | 12.9 (1.7) | 10.6 (1.6) | 10.7 (1.7) | 8.8 (1.1) | 9.1 (1.5) | 10.2 (1.9) | 10.7 (2.2) | 0.002 |
| ICH/PVL, n (%)§ | 4 (29%) | 1 (33%) | 34 (27%) | 0 (0%) | 42 (24%) | 4 (9%) | 25 (15%) | 4 (4%) | 20 (10%) | 9 (10%) | 16 (7%) | 17 (8%) | 61 (10%) | 0.34 |
| Necrotising enterocolitis, n (%) | 0 (0%) | 0 (0%) | 19/127 (15%) | 1 (10%) | 17 (10%) | 2 (5%) | 13 (8%) | 8 (9%) | 9 (4%) | 1 (1%) | 6/241 (2%) | 11 (5%) | 28/620 (5%) | 0.79 |
| Survived to 7 days, n (%) | 6 (43%) | 1 (33%) | 95 (74%) | 9 (90%) | 146 (83%) | 41 (95%) | 151 (89%) | 89 (100%) | 193 (92%) | 89 (99%) | 222 (92%) | 219 (99%) | 566 (91%) | <0.001 |
| Survived to PMA 36 weeks, n (%) | 5 (36%) | 1 (33%) | 71 (55%) | 8 (80%) | 124 (70%) | 40 (93%) | 137 (81%) | 83 (93%) | 183 (87%) | 86 (96%) | 212 (88%) | 209 (94%) | 532 (86%) | <0.001 |
| Survived to PMA 40 weeks, n (%) | 5 (36%) | 1 (33%) | 71 (55%) | 8 (80%) | 123 (70%) | 40 (93%) | 137 (81%) | 83 (93%) | 181 (86%) | 85 (94%) | 212 (88%) | 208 (94%) | 530 (85%) | <0.001 |
| MV, n (%) | 14 (100%) | 2 (67%) | 127 (99%) | 9 (90%) | 174 (99%) | 37 (86%) | 163 (96%) | 52 (58%) | 175 (83%) | 49 (54%) | 168 (69%) | 138 (62%) | 506 (81%) | <0.001 |
| Days on MV, all infants, mean (SD) (Q1, Q2, Q3) | 20 (29) (2, 5, 33) | 12 (19) (1, 2, 18) | 31 (35) (7, 26, 43) | 19 (12) (10, 22, 26) | 28 (32) (9, 24, 37) | 16 (14) (3, 12, 28) | 18 (19) (4, 12, 28) | 8 (10) (0, 3, 12) | 11 (25) (1, 5, 14) | 5 (10) (0, 2, 6) | 6 (12) (0, 2, 6) | 8 (12) (0, 3, 12) | 11 (20) (1, 5, 14) | 0.007 |
| Days on MV, ventilated infants, mean (SD) (Q1, Q2, Q3) | 20 (29) (2, 5, 33) | 18 (23) (10, 18, 26) | 31 (35) (8, 26, 44) | 21 (11) (19, 23, 26) | 29 (33) (10, 24, 37) | 18 (14) (7, 17, 28) | 19 (19) (5, 12, 29) | 13 (11) (5, 10, 19) | 14 (27) (2, 6, 15) | 10 (11) (3, 6, 15) | 9 (14) (2, 4, 9) | 13 (12) (4, 9, 20) | 14 (21) (2, 7, 17) | 0.69 |
| Days on MV, survived to PMA 36, mean (SD) (Q1, Q2, Q3) | 51 (30) (33, 33, 56) | 34 (–) (34, 34, 34) | 47 (38) (30, 38, 54) | 22 (10) (21, 24, 26) | 35 (35) (19, 29, 42) | 16 (14) (3, 13, 28) | 20 (20) (5, 15, 30) | 8 (11) (0, 3, 12) | 12 (26) (1, 5, 14) | 5 (10) (0, 1, 6) | 6 (12) (0, 2, 6) | 8 (12) (0, 3, 12) | 12 (21) (1, 5, 15) | 0.005 |
| Days on MV, survived to PMA 36 and ventilated, mean (SD) (Q1, Q2, Q3) | 51 (30) (33, 33, 56) | 34 (–) (34, 34, 34) | 47 (38) (30, 38, 54) | 26 (6) (22, 25, 26) | 35 (35) (20, 29, 42) | 18 (14) (8, 17, 28) | 21 (20) (6, 16, 30) | 14 (11) (5, 11, 20) | 15 (28) (2, 7, 16) | 10 (11) (3, 6, 14) | 9 (14) (2, 5, 10) | 14 (12) (4, 9, 20) | 15 (22) (3, 8, 18) | 0.41 |
| BPD-36¶, n (%) | 3/5 (60%) | 1/1 (100%) | 62/71 (87%) | 4/8 (50%) | 97/124 (78%) | 18/40 (45%) | 81/137 (59%) | 40/83 (48%) | 104/183 (57%) | 29/86 (34%) | 83/212 (39%) | 87/209 (42%) | 268/532 (50%) | 0.03 |
| BPD-40¶, n (%) | 3/5 (60%) | 1/1 (100%) | 32/71 (45%) | 0/8 (0%) | 48/123 (39%) | 4/40 (10%) | 27/137 (20%) | 12/83 (14%) | 37/181 (20%) | 9/85 (11%) | 21/212 (10%) | 25/208 (12%) | 85/530 (16%) | 0.17 |
| Survived without BPD at PMA 36, n (%) | 2/14 (14%) | 0/3 (0%) | 7/128 (5%) | 4/10 (40%) | 26/176 (15%) | 22/43 (51%) | 55/169 (33%) | 42/89 (47%) | 79/210 (38%) | 56/90 (62%) | 128/242 (53%) | 120/222 (54%) | 262/621 (42%) | 0.002 |
| Survived without BPD at PMA 40, n (%) | 2/14 (14%) | 0/3 (0%) | 37/128 (29%) | 8/10 (80%) | 74/176 (42%) | 36/43 (84%) | 109/169 (64%) | 70/89 (79%) | 144/210 (69%) | 75/90 (83%) | 190/242 (79%) | 181/222 (82%) | 443/621 (71%) | 0.003 |
Statistical analyses are limited to infants born at 25–27 weeks’ gestational age.
*No infants born at 22 weeks received LISA.
†Limited to gestational age 25–27 weeks, Welch’s t-test or χ2 test.
‡Birth weight below the 10th percentile.
§Intracranial haemorrhage grade 3–4 and/or cystic periventricular leukomalacia.
¶Only infants who survived to PMA 36/PMA 40 weeks.
BPD-36 and BPD-40, supplemental oxygen or positive respiratory support at 36 and 40 weeks’ PMA; ICH/PVL, intracranial haemorrhage/cystic periventricular leukomalacia; LISA, less invasive surfactant administration; MV, mechanical ventilation; n, number of infants; NEC, necrotising enterocolitis; PMA, postmenstrual age; Q1, 1st quartile; Q2, median (2nd quartile); Q3, 3rd quartile; SGA, small for gestational age.