Obese female mice have lower fertility than healthy weight
mice, according to a study led by researchers from the University of Adelaide
In the research the unlicensed experimental drugs salubrinal and
BGP-15 - which is currently being tested in clinical trials as a treatment for type 2 diabetes - increased the number and
quality of eggs produced by obese mice.
Despite a flurry of newspaper headlines proclaiming, for
example, that 'health risks for
obese mothers and their babies can be reversed', the 'immediate impact of this research to women is minimal'
according to NHS Choices.
In the study, mice with a genetic predisposition to obesity -
so-called 'Blobby mice' - were given IVF drugs to stimulate egg production. Obese
Blobby mice produced fewer eggs than normal healthy weight mice, and the eggs
they produced had signs of damage to the mitochondria, the miniature 'powerhouses'
Dr Rebecca Robker, a cell biologist and lead author of the
study, said: 'Obesity can result in altered growth of babies
during pregnancy and it permanently programs the metabolism of offspring,
passing the damage caused by obesity from one generation to the next.'
In humans, obesity is associated with reduced fertility and
higher risk of complications in pregnancy including miscarriage and stillbirth.
Obese mothers are more likely to have overweight children and, although the
biological mechanism is unclear, this is likely to result from both
environmental and genetic factors.
The research also showed that when fertilised eggs from
obese Blobby mice were implanted into normal weight mice, the resulting fetuses were heavier
and had less mitochondrial DNA than fetuses from normal weight mice.
Experimental drug treatment given to obese Blobby mice before egg collection,
however, increased both the number of eggs and mitochondrial activity to normal
Dr Robker says that the drugs 'were highly successful in
preventing the stress response, thereby stopping the damage from obesity being
passed on to the offspring'.
In fact, the idea that reduced mitochondrial
activity can give rise to obesity in the offspring, is not yet established,
but, says NHS Choices, remains a 'plausible explanation that will require
Furthermore, the drugs used in the study are unlicensed, although
BGP-15 is currently in trials. Neither has been tested in humans as part of any
Professor Adam Balen, chair of the British Fertility Society,
who was not involved in the study, told the Independent that, while any drug
treatment was a long way off, the findings were 'very interesting'.
He added that the important message to take away from the study is that 'women
need to be nutritionally healthy before they get pregnant'.