| Male sex | 64 (60.4) |
| Ethnic group | |
| White | 52 (48.1) |
| Asian/Asian British | 18 (16.7) |
| Black/black British | 11 (10.1) |
| Mixed | 11 (10.1) |
| Other | 16 (14.8) |
| Birth weight (g), mean (SD) | 3170 (480) |
| Gestational age (weeks), mean (SD) | 38.2 (1.7) |
| Mode of delivery | |
| Normal vaginal | 63 (58.3) |
| Instrumental vaginal | 25 (23.1) |
| Caesarean section | 20 (18.5) |
| Feeding method | |
| Breast | 87 (80.5) |
| Artificial | 13 (12.0) |
| Mixed | 6 (5.5) |
| Associated problems | |
| Suspected haemolysis | 49 |
| Rhesus incompatibility | 6 |
| Probable ABO incompatibility | 16 |
| Possible ABO incompatibility | 17 |
| Glucose 6-phosphate dehydrogenase deficiency | 5 |
| Hereditary spherocytosis | 3 |
| Other causes of haemolysis | 2 |
| Dehydration | 30 |
| Bruising | 7 |
| Sepsis | 4 |
| Miscellaneous | 4 |
| No associated pathology | 29 |