Skin to perichondrium distance by gestational age group
| <33 weeks | 33–<37 weeks | ⩾ 37 weeks | |
|---|---|---|---|
| The group <33 weeks gestation has a greater proportion of SPDs <3 mm than the other two groups (Fisher exact test, p<0.01). There is no significant difference between the other two groups. | |||
| External | |||
| <3 mm | 11 (32%) | 6 (9%) | 4 (4%) |
| ⩾3 mm | 23 (68%) | 60 (91%) | 101 (96%) |
| Midline | |||
| <3 mm | 13 (38%) | 5 (8%) | 3 (3%) |
| ⩾3 mm | 21 (62%) | 61 (92%) | 102 (97%) |
| Internal | |||
| <3 mm | 15 (44%) | 5 (8%) | 2 (2%) |
| ⩾3 mm | 19 (60%) | 61 (92%) | 103 (98%) |