The government should take on board findings of a New Zealand fertility study, so that politicians better understand the stressors young Kiwis are loaded with, a neuroendocrinologist says.
File photo. Photo: 123RF
New Zealand scientists have found the missing link that proves stress can stop you getting pregnant. For a decade they've studied a group of neurons in the brain that control female reproduction like a switch.
Professor Greg Anderson, of the Centre for Neuroendocrinology at the University of Otago, told Morning Report modern living was a factor in rates of fertility and that stress hormones impacted on neurons that drove the reproductive system.
Professor Anderson said there had always been a recognised but poorly understood link between stress and fertility. The study, however, had identified a brain-reproductive system axis that explained the nature of that link.
"I think just an understanding of that is important for couples trying to conceive and maybe it's another thing that the government needs to take onboard when understanding just how many stressors young people are loaded with these days," he said.
His comments come after it was revealed last month New Zealand had recorded its lowest-ever fertility rate.
The latest quarterly data from Stats NZ showed the ratio of births to the number of women of child-bearing age was now 1.63 - well below the 2.1 ratio needed to keep the population growing.
"We find ourselves in a situation now where we could be shutting down fertility just because of someone's career" - Professor Greg Anderson, Centre of Neuroendocrinology at the University of Otago
The study identified a neural pathway between the brain and reproductive system that served to shutdown chances of conceiving in times of chronic stress.
"What we've discovered in a small number of cells, maybe 1000 cells, located at the base of the brain and they are somehow able to sense stress," he said.
"Maybe it's stress hormones like cortisol and when they sense that they send a signal to the reproductive system and they shut it down.
In evolutionary terms, this neuronal wiring would make sense, in that it served a purpose of avoiding birth when circumstances were dire, he said.
However, because modern life involves long periods of enduring chronic stress this biological safety mechanism could play a negative role and stop couples conceiving at all.
"In ancient times that may be a useful system. You don't want to have kids in times of war and so on, but we find ourselves in a situation now where we could be shutting down fertility just because of someone's career. That's the thing we really want to understand and resolve."
He said in the future, the group of brain cells could potentially be targeted by drugs to block the stress signal, leaving the reproductive system unaffected. RF-amide related peptide 3 (RFRP-3) is the neuropeptide thought to inhibit central regulation of fertility.
In the meantime, simply understanding the effects of chronic stress on reproduction was important and could help mitigate the problem with preventive methods of relaxation and stress avoidance.
Another crippling stress is that of not being able to conceive, locking couples into a vicious cycle, he said.
Anderson said both sexes had the cluster of cells, but studies had shown the system seemed to operate most potently in women.
"In females these cells really seem to be active in shutting down the reproductive system in times of stress.
"We don't understand why that difference is, but it kind of makes sense in terms of evolutionary thinking, because women traditionally have borne the greatest brunt of raising children... that they are unconsciously able to regulate their fertility in times of stress."