The UN health agency said Thursday it has revised a benchmark used by health professionals worldwide in caring for women during childbirth because it has caused a surge in interventions like caesarean sections that could be unnecessary.
Since the 1950s, a woman progressing through labour at a rate slower than one centimetre of cervical dilation per hour has been considered "abnormal", said Olufemi Oladapo, a medical officer with the World Health Organization's department of reproductive health.
When doctors and other care providers confront labour moving slower than that rate, "the tendency is to act", either with a caesarean section or with the use of drugs like oxytocin that speed up labour, leading to the "increased medicalisation" of childbirth, he said.
In new guidelines unveiled Thursday, the WHO called for the elimination of the one centimetre per hour benchmark.
"Recent research has show that that line does not apply to all women and every birth is unique," Oladapo told reporters in Geneva.
"The recommendation that we are making now is that that line should not be used to identify women at risk of adverse outcome," he added.
While rates of interventions like c-sections vary among regions, WHO has seen what it considers a worrying rise in such practices worldwide.
Interventions that were once used to manage complicated childbirths have become commonplace, the agency warned.
"Pregnancy is not a disease and child birth is a normal phenomenon, where you expect the woman to be able to accomplish that on her own without interventions," Oladapo said.
"However, what has been happening over the last two decades is we have been having more and more medical interventions being applied unnecessarily to women and we have situations where several woman are getting too many interventions that they do not need."
While cautioning against any one-size-fits-all benchmarks, the new WHO guidelines say that for a woman delivering her first child, any labour that does not extend beyond 12 hours should be considered normal.
For a subsequent pregnancy, the figure drops to less than 10 hours.