Individual antenatal and perinatal factors
| Antenatal factors | Perinatal factors |
| Amniocentesis | Abnormal cardiotocography |
| Intrauterine growth retardation | Abnormal Apgar scores |
| Reduced amniotic fluid | Low cord pH |
| Reduced fetal movements | Presence of meconium (grade I–III) |
| Infection | |
| Bleeding | |
| High blood pressure | |
| Unexplained abdominal pain | |
| Trauma | |
| In vitro fertilisation | |
| Breech position |