Girl and Boy babies have different responses to a mother's stress during pregnancy, such as being in poor health or suffering psychological stress, researchers say. "What we have found is that male and female babies will respond to stress during pregnancy by adjusting their growth patterns differently," study leader Vicki Clifton, an associate professor in the pregnancy and development group of the Robinson Institute at the University of Adelaide, said in a news release. "The male, when mom is stressed, pretends it's not happening and keeps growing, so he can be as big as he possibly can be. The female, in response to mom's stress, will reduce her growth rate a little bit; not too much so she becomes growth restricted, but just dropping a bit below average," Clifton explained. "When there is another complication in the pregnancy -- either a different stress or the same one again -- the female will continue to grow on that same pathway and do OK, but the male baby doesn't do so well and is at greater risk of pre-term delivery or will stop growing." This research could lead to better outcomes for women with at-risk pregnancies. "We are looking at what events during pregnancy cause changes in how the baby grows, what's behind this and ways in which we can improve the outcomes for pregnant women and their babies," Clifton said.