It appears that girls have better survival rates than men, showing yet again the benefits of being female at birth, a new study in the journal Medical Human Reproduction reported. The findings revealed that male babies as a whole have poorer health results than their female counterparts and could shed light on why female babies likely do better in harder conditions.
The study was conducted by researchers from Australia's University of Adelaide and looked at previous research that suggests male babies grow faster than female babies in the womb and are larger and weigh more on average than girls.
But this comes at a negative consequence, the researchers found. While some researchers say the male placenta functions more efficiently, researchers say this fast growth and larger size leaves them susceptible to adverse health conditions.
The study said that this can often lead to undernutrition in the womb, which can reduce the baby's ability to grow and can lower the birthweight, leading to cardiovascular diseases when the child reaches an adult age.
"Our research has found that there are undeniable genetic and physiological differences between boys and girls that extend beyond just the development of their sexual characteristics," Professor Claire Roberts, leader of the fetal growth research priority for the Robinson Research Institute and senior author of the paper, says in a news release.
She continues that research has clearly shown for a while now that girls are beating boys on survival rates, and says that the placenta may hold the key to understanding why male babies, in both human and other animals, grow faster and larger than females.
"Our results suggest that there is a distinct sex bias in the regulation of genes in the human placenta," lead author Sam Buckberry of the University of Adelaide also says in the news release of the study.
The research shows that there is a higher gene expression in female babies in placental development and this "suggests that girls are more likely to adopt a risk-averse strategy towards development and survival," Buckberry says.
Overall, this means that if you are expecting a girl, the likelihood of a healthy child is dramatically higher than if you were having a boy.
"These findings may be important to help guide future sex-specific therapeutics for pregnant women and for babies in the neonatal nursery," Roberts concluded.
For now, the researchers suggested further studies be done in order to better understand the phenomenon and how to use it to increase health of babies, male or female.