Sydney: Know why there are significantly increased rates of pregnancy complications and poor health outcomes for baby boys? Because there is a distinct sex bias in the regulation of genes in the human placenta that makes girl babies win the battle for survival.
According to a significant study, male and female babies develop in very different ways and the placenta plays a key role in these gender differences.
“There are undeniable genetic and physiological differences between boys and girls that extend beyond just the development of their sexual characteristics,” said professor Claire Roberts, leader of the foetal growth research priority for the Robinson Research Institute at University of Adelaide.
Scientists have known for some time that girls are clearly winning in the battle for survival - with markedly better outcomes for female babies for preterm birth, stillbirth, neonatal death and other complications after birth.
“Male babies generally grow faster and bigger than females. This occurs in both the animal and human worlds, but until now we haven't really understood how or why,” professor Roberts noted.
The researchers compared the genes expressed in 300 placenta samples and found that more than 140 genes were expressed differently across male and female samples.
They found that with female babies, there is much higher expression of genes involved in placentaldevelopment, the maintenance of pregnancy and maternal immune tolerance.
“This suggests that girls are more likely to adopt a risk-averse strategy towards development and survival, and it goes some way to explaining the differences in male and female development in the womb,” said lead author Sam Buckberry, a PhD student at University of Adelaide.
These findings may be important to help guide future sex-specific therapeutics for pregnant women and for babies in the neonatal nursery, said the study published in the journal Molecular Human Reproduction.