.... Male and female [fetuses] ... show different growth and development patterns following stressors during pregnancy such as disease, cigarette use or psychological stress.
... "The male, when mum is stressed, pretends it's not happening and keeps growing ... The female ... will reduce her growth rate a little bit; not too much so she becomes growth restricted, but just dropping a bit below average.
"When there is another complication in the pregnancy ... the female will continue to grow on that same pathway and do okay but the male baby doesn't do so well and is at greater risk of pre-term delivery, stopping growing or dying in the uterus."
... this ... growth response had been observed in pregnancies complicated by asthma, pre-eclampsia and cigarette use [and] psychological stress ...