It showed that the risk of permanent harm linked with spinal anaesthetic or epidural was about one in 23,000 to one in 50,000.
Permanent injury in the study was defined as symptoms lasting more than six months.
The risk of being paralysed was two to three times less than of suffering any permanent harm.
Besides, the risk for women requiring pain relief for labour or Caesarean section was still lower, and the most pessimistic estimate of permanent harm was one in 80,000.
It was found, the risk of harm associated with epidural use during surgery was considerably higher than during childbirth, between one in 6,000 and one in 12,000.
However, even that was lower than previous estimates.
Cook said that the reason behind higher risk could be that many patients were elderly with medical problems, "and that the surgery itself increases risks," reports The Independent.
The study was published in the British Journal of Anaesthesia.