College of Medicine & Veterinary Medicine

Stress in womb takes greater toll on males, study shows

Exposure to stress in the womb could be more harmful to males after birth than females, researchers have found.

A study shows that when female mice are exposed to stressful situations early in pregnancy - such as being placed in unfamiliar surroundings, changing cages multiple times in a day, or smelling the odour of a predator - their male offspring are more sensitive to stress than females.

This increased sensitivity to stress and behaviour and behaviour displayed may be similar to aspects of developmental brain disease in humans.

As adults, these males also presented with smaller testes and lower testosterone levels, indicating an impact of the mother’s stress on their fetal development. Interestingly, these effects were also passed on to the next generation - from father to son.

The findings by the University of Pennsylvania will be presented this week at the Parental Brain conference organised by the University of Edinburgh.

Stress in the womb is known to increase the risk of disease in offspring, including autism schizophrenia, anxiety, heart disease, obesity and diabetes. Understanding the connection between the mother’s changing environment and the long-term impact on offspring disease susceptibility may help to develop new therapeutic treatments or preventions.

Researchers believe that the placenta - which is grown mostly from fetal tissue - develops in a different way for males than it does for females. It is thought that the placenta, as the interface between mother and baby, has an important buffering role to protect the unborn baby.

Scientists say that sex differences here may affect the way that hormones and nutrients pass from mothers to their young through the placenta, and could lead to differences between how the mother’s stress affects male and female babies.

Experts at the conference will also present new research showing how the adverse effects of stress on babies can be reversed through increased maternal attention and physical contact after birth.

Understanding how bad experiences in very early life can have lifelong harmful effects on mental and physical health, will lead to better ways to prevent and to overcome these problems. It has become obvious that many adult health problems have their origins even in the womb, and this is especially relevant to the campaign to improve the health of people, including in Scotland

Prof John Russellof the University of Edinburgh

The conference will begin on Wednesday and run until 4 September. More than 150 experts from around the world will meet to discuss the way the brain changes as a result of parenthood.