Patient and disease characteristics
| Age ≤5 years and respiratory support at birth (n=82) | All patients (N=145) | |
| Age at XLMTM genetic diagnosis (months),* n | 80 | 142 |
| Mean (SD) | 6.5 (7.5) | 33.0 (61.3) |
| Quartiles (25th, median, 75th) | 2, 4, 7 | 3, 6, 27 |
| Decreased fetal movement, n/N (%) | 44/82 (53.7) | 75/142 (52.8) |
| Weeks when decreased fetal movement noted, n | 10 | 17 |
| Mean (SD) | 29.7 (4.6) | 28.6 (4.6) |
| Quartiles (25th, median, 75th) | 28, 31, 34 | 25, 29, 32 |
| Polyhydramnios, n/N (%) | 44/82 (53.7) | 70/142 (49.3) |
| Weeks when polyhydramnios noted, n | 24 | 31 |
| Mean (SD) | 30.9 (5.8) | 30.8 (5.4) |
| Quartiles (25th, median, 75th) | 28, 32, 36 | 28, 31, 36 |
| Premature (<36 weeks) delivery,† n/N (%) | 28/82 (34.1) | 43/142 (30.3) |
| Weeks at premature delivery, n | 28 | 43 |
| Mean (SD) | 32.4 (2.3) | 32.6 (2.2) |
| Quartiles (25th, median, 75th) | 31, 33, 34 | 31, 33, 34 |
| Apgar score 1 min after birth, n (%) | 65 | 102 |
| ≥7 (normal) | 2 (3.1) | 8 (7.8) |
| 4–6 (intermediate) | 13 (20.0) | 23 (22.5) |
| 0–3 (low) | 50 (76.9) | 71 (69.6) |
| Apgar score 5 min after birth, n (%) | 64 | 100 |
| ≥7 (normal) | 11 (17.2) | 24 (24.0) |
| 4–6 (intermediate) | 34 (53.1) | 51 (51.0) |
| 0–3 (low) | 19 (29.7) | 25 (25.0) |
| Type of respiratory support required first 24 hours after birth, n (%) | 82 | 133 |
| IPPV/SIMV/pressure support | 44 (53.7) | 71 (53.4) |
| CPAP/BiPAP | 24 (29.3) | 31 (23.3) |
| Supplemental oxygen | 3 (3.7) | 7 (5.3) |
| Not documented | 11 (13.4) | 24 (18.0) |
Column header counts are the number of patients who have non-missing mortality data. For each characteristic, n refers to the number of patients with non-missing data for that characteristic.
*Age at diagnosis was calculated using the date of genetic confirmation.
†Premature delivery was defined as delivery before 36 weeks.
BiPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; IPPV, intermittent positive pressure ventilation; SIMV, synchronised intermittent mechanical ventilation; XLMTM, X-linked myotubular myopathy.