'Lean, mean' baby girls better combat stress in womb

Research shows female foetuses are more resilient and better able to cope with multiple stresses before birth. Photo / Northern Advocate

Baby girls are "lean and mean" and better able to cope with stress while in the womb, new research has found.

For the first time studies at the University of Adelaide's Robinson Institute have established differences in how baby girls and boys cope with stress during pregnancy.

Faced with issues like a mother smoking, drinking alcohol, suffering from asthma or having an infection, the girls appear more resilient and better able to cope with multiple events before birth.

But the news isn't all bad for boys, with the research also showing they do better than girls if the mother only faces a single stress, like asthma, or a single infection.

"Basically, what we see, when mum has a stressful event during pregnancy, is that boys make themselves as big as they possibly can and ignore what is happening in mum's body," Associate Professor Vicki Clifton told reporters.

"Girls make themselves just a little bit smaller and that means that they have a greater chance of surviving if something else goes wrong in the pregnancy.

"With boys, if something else goes wrong, they are more at risk of delivering pre-term or, in the worst case scenario, being stillborn."

"So in the uterus girls do cope better with stresses than boys.

"Girls are lean and mean and they're survivors."

Prof Clifton said the explanation for the differences lay with the movement of stress hormones across the placenta.

Girls make big adjustments to the presence of stress hormones while boys try to ignore them, which could impact on their chances of making it to full term or having health issues after birth.

Prof Clifton said it was hoped her research would help better educate potential and pregnant mothers about the risks associated with habits such as smoking and alcohol use, and the possible impact on their babies.

It should also help educate women on the need to take good care of themselves during pregnancy, including watching their diet and better managing conditions such as asthma.

A mother involved in the study, Marnie Hillier, said she noticed her asthma, which had not required medication for 10 years, returned when she became pregnant with her first child.

She said the research helped reassure her that taking her medication was less of a health risk and more important to reduce the stress on her baby.

"This research will help educate people that what we do in the early stages of pregnancy can have a big impact on the children that we have," Ms Hillier said.

"I think it's important to have an awareness. There are some things that are beyond our control but the things that we can manage...it's really important that you think about the impact on the significant being that's growing inside of you."

- AAP