A 12-year health study in Adelaide found out that female fetus finds it quicker to deal with prolonged stress during pregnancy.

The study from the University of Adelaide has found out that females have a steadier growth pattern if stress issues continue to be a concern for the mother while male fetuses initially better handle stress factors such as smoking.

Professor Vicki Clifton, the lead researcher for the study, says male fetuses often need greater protection.

Male fetuses stop growing and become growth restricted or deliver pre-term. In the worst case scenario they could end up being stillborn, but this is a very rare scenario.

Professor Clifton said the results they got will help develop sex-specific therapies and more accurate growth and development predictions for fetuses at risk.

We have been surprised by the results because it changes the way we think about the growth of fetuses, Professor Clifton said.

In the past we thought that male and female fetuses grow through the same mechanisms, but our latest data's starting to show that male and female babies institute varying mechanisms to cope with a stress.