Women who suffer extreme stress in the early stages of pregnancy are more likely to give birth to children who develop schizophrenia, a major international study shows.
The research looked at women living in war zones, but Australian psychiatry experts say the findings confirm the dangers of all types of stress from domestic violence to bereavement on unborn babies.
Schizophrenia is a complex brain disorder, characterised by delusions and hallucinations, that usually strikes in early adulthood - and with often devastating results.
It is most commonly passed down through families, but environmental factors like drugs and stress are also thought to be involved.
New research by scientists at New York University's School of Medicine has proven conclusively that wartime stress is a trigger in a study of 88,829 people born in Jerusalem, Israel.
They found that the children of women who were in their second month of pregnancy during the height of the Arab-Israel war in June of 1967, the so-called "Six Day War", showed a significantly higher rate of schizophrenia as they entered adulthood.
Female offspring were much more likely to be affected than males.
"It's a very striking confirmation of something that has been suspected for quite some time", said lead researcher Professor Dolores Malaspina.
"The placenta is very sensitive to stress hormones in the mother. These hormones were probably amplified during the time of the war."
The maximum period of impact occurred early in the gestation period, especially in the second month, said the study, published in the Britain-based open access journal BioMed Central Psychiatry.
Professor Jayashri Kulkarni, director of the Alfred Psychiatry Research Centre at Monash University in Melbourne, said the in vitro stress hypothesis had been under investigation by clinicians for some time.
"What we have here is confirmation that it really is a major factor," Prof Kulkarni said.
She said hormones released by the body in times of stress were implicated in brain development and were known to have major multiple flow-on effects in the body.
"If it has been shown that wars can impact a baby's brain development in this way then it follows that other types of stress like domestic violence, severe anxiety, bereavement or other types of loss could have the same effect," the professor said.
Studies have shown poor nutrition and influenza during pregnancy could also increase risk.
"There's an important message here and we need to ensure it is translated into preventative work in pregnant women to reduce the risk," Prof Kulkarni said.
