The proverbial question of “Mars” and “Venus” appears to get a very early start in humans.
Pronounced differences in male and female behaviors can be detected in the womb, according to Australian medical researchers, who say the sex of the baby determines responses to gestational situations.
Those responses are specific and telling.
“The male, when mum is stressed, pretends it’s not happening and keeps growing, so he can be as big as he possibly can be,” said Vicki Clifton, an associate professor of obstetrics and gynecology at the University of Adelaide who led the study.
“The female, in response to mum’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.”
Ms. Clifton and her team studied the growth and development of fetuses whose mothers were under psychological stress or had asthma, serious medical conditions or high blood pressure.
“What we have found is that male and female babies will respond to a stress during pregnancy by adjusting their growth patterns differently,” Ms. Clifton said.
Some of the findings were dramatic.
“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,” Ms. Clifton said, “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.”
The “sex-specific growth pattern” became apparent when the mothers-to-be had increased levels of the stress hormone cortisol in their blood, which then was passed on to their babies through the placenta.
Ms. Clifton said her findings could lead to “sex-specific therapies” for mothers at risk for premature birth and also could help obstetricians more accurately interpret growth and development of the fetus.
Meanwhile, other research has revealed much about the unborn.
In 2009, a Dutch team of obstetricians determined that fetuses are capable of having memories at about 30 weeks of gestation - or two months before they are born. The researchers used sound and vibration stimulation, combined with sonography, to show evidence of short-term memory in the unborn, based on their eye, mouth and body movements.
A hospital study determined the smallest victims of the Sept. 11 attacks on the World Trade Center. Pregnant women who escaped the burning Twin Towers passed on the stress of the experience to their unborn babies in a “ripple effect,” New York’s Mount Sinai Hospital reported in 2005.
Researchers followed 38 expectant mothers who lived through the attack to determine whether they showed signs of post-traumatic stress disorder, measuring the levels of cortisol in mothers and infants. The study found that though the babies “were far too young to comprehend or identify with their mother’s anxiety, the physical markers were present nonetheless.”