A specific gene variant has been found that may be linked to reduced pain in childbirth.
Dr Michael Lee and his team at the University of Cambridge, UK, investigated why some women experience less pain during labour. They studied a group of women who did not request analgesia during their first delivery.
The results of sensory and psychometric tests were normal, apart from a higher pain threshold for pressure-related pain.
Genetics tests revealed “an excess of heterozygotes carrying the rare form of the single nucleotide polymorphism rs140124801 in the KCNG4 gene”. These single nucleotide polymorphisms are the most common type of genetic variation among individuals.
The researchers explain that this genetic variant limits the ability of nerve cells to send pain signals to the brain. The finding was later confirmed on tests using rodents.
In Cell Reports yesterday (21 July) they write: “We conclude that KCNG4 can influence human labour pain by modulating the excitability of uterine nociceptors.”
Co-author Dr St. John Smith said that the genetic variant “acts like a natural epidural”.
He said: “It means it takes a much greater signal – in other words, stronger contractions during labour – to switch it on. This makes it less likely that pain signals can reach the brain.”
The team hope that their finding can open avenues to the development of new drugs to manage pain.
Commenting on the work, Zeenath Uddin of the Royal College of Midwives, said: “Every woman is different, and every birth is unique; what is important is that you get the pain relief that is right for you. This will include pain relief such as injections, tablets and Entonox, and ways to manage the pain including relaxation and distraction techniques, massage, and water birth.”
Lee, M.C. et al. Human labour pain is influenced by the voltage-gated potassium channel Kv6.4 subunit. Cell Reports 21 July 2020; doi: 10.1016/j.celrep.2020.107941
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