A study has found that the trauma experienced by a mother prior to pregnancy will influence her offspring's behaviour.
The study was conducted on rats at the University of Haifa.
"The findings show that trauma from a mother's past, which does not directly impact her pregnancy, will affect her offspring's emotional and social behaviour. We should consider whether such effects occur in humans too," said Prof. Micah Leshem, who carried out the study.
Earlier studies have researched trauma during pregnancy, this is the first study to investigate trauma prior to conception.
Rats were used in the investigation as they have found to behave socially in a similar way to humans.
Researchers examined three groups of rats: one group was put through a series of stress-inducing activities two weeks before mating, allowing the female time to recover before becoming pregnant; the second group was similarly treated over the course of a week immediately prior to mating; and the third, control group, were not given any form of stress.
Once the offspring of the rats had matured and were over 60 days old, their social and emotional behaviour, such as amount of anxiety and depression, was evaluated.
The study found that trauma experienced by the females prior to conception had varied effects on the offspring.
According to Leshem, these effects varied between groups and between male and female offspring; but their behaviour was without doubt different from that of the rats from the control group.
All the offspring of stressed mothers showed reduced social contact compared with that of the control mothers' offspring: these rats spent less time with one another and interacted less.
In other tests, there were important sex differences. The female rats displayed more symptoms of anxiety, while the males exhibited less anxiety.
Finally, those rats whose mothers became pregnant immediately after being stressed were hyperactive, indicating that how long before pregnancy adversity is experienced, is also important.
"The findings of the present study show that adversity from a mother's past, even well before her pregnancy, does affect her offspring, even when they are adult," Leshem said.
The study is published in the journal Developmental Psychology.