A new international study has investigated the factors, including biological influences that may be behind the severe decline in child births that has occurred over the past 50 years.
Just published in the leading medical periodical, Nature Reviews Endocrinology, the study has examined whether this decline can be explained by economic and behavioural factors alone or to what degree biological factors are also a contributor.
Contributing author, Head of Fertility Services, King Edward Memorial Hospital and WIRF Research Fellow, Prof Roger Hart, pointed to data suggesting that human reproductive health continued to deteriorate in industrialised regions.
Widespread infertility and the need for assisted reproduction due to poor semen quality and reduced natural conception rates are now major health issues. Other indicators of declining reproductive health include a worldwide increasing incidence in testicular cancer among young men and alterations in twinning frequency.
Prof Hart said subtle alterations in fertility rates were already visible by the early 1900s.
“Most industrialised regions now have rates below levels required to sustain their populations,” Prof Hart said.
“The study team hypothesise that declines in fertility rates might be linked to exposures to chemicals originating from fossil fuels causing human reproductive problems and cancer; early gestation might be a sensitive period.
“A key research challenge remains on how to distinguish biological from socioeconomic and behavioural factors.”
If the current infertility epidemic is indeed linked to such exposures, decisive regulatory action underpinned by interdisciplinary research collaborations may be needed to reverse the trends.
The paper, ‘Environmental factors in declining human fertility’ has been published online and can be viewed here.
