Hormonal changes that occur during childbirth may enable women to develop natural barriers against the onset of chronic pain after delivery, two separate studies from the US have confirmed.
The first study, which will appear in the January issue of US journal Anesthesiology, analysed the levels of pain experienced by 1,228 women at varying time intervals post childbirth. Only 1.8% of the women reported experiences of pain six months after delivery. This proportion dropped to 0.3% of women who were still experiencing pain 12 months after labour.
The results suggested that the process of childbirth activated a protecting mechanism, which prevented chronic pain from developing after the physical injury of labour had been incurred.
A second study, conducted by researchers at the Wake Forest School of Medicine in Winston-Salem, found that elevated oxytocin levels in the brain and spinal cord helped mothers to protect themselves against chronic hypersensitivity in the post-partum period.
One of the study authors, Dr James Eisenach, said the findings helped to explain the remarkably low rates of chronic pain experienced by mothers in the original study.
He said: “Oxytocin in the brain is considered important to mother-baby bonding, trust, love and social engagement. These results suggest the surge in oxytocin around childbirth may also speed recovery from the pain caused by childbirth.”
During the second study, researchers injected laboratory rats with an oxytocin antagonist called atosiban, which worked to delay the recovery of the rats after they had given birth. Many were also separated from their pups, which caused their maternal release of oxytocin to decrease, thereby delaying their recovery from labour-induced nerve damage.
Dr Eisenach was confident that the implications of these findings range could far beyond pregnancy and childbirth. He suggested they could inform therapies for dealing with chronic pain caused by many other types of injuries and illnesses.