This is unclear. The strongest association is with trauma and hypertension.
Other factors which have been associated with abruption are:
- past obstetric history of abruptio placentae
- pregnancy induced or essential hypertension - in up to 25% of patients with abruption
- multiple pregnancy
- increasing age
- high parity
- low socio-economic status
- renal infection
- drugs - smoking, cocaine
- uterine anomaly or tumour
- sudden uterine decompression - may endanger the second or subsequent children in multiple births
- short umbilical cord
- pressure from the enlarged uterus on the inferior vena cava
It has been suggested also that abruption may be caused by folate deficiency because:
- abruptio placentae is found more often in multiparous women with low socio-economic status
- there is an association between megaloblastic anaemia and abruption However:
- megaloblastic anaemia is common in Nigeria but abruption is not
- folate supplements are not protective