May 12 2009
A mother who experienced trauma prior to becoming pregnant affects the emotional and social behavior of her offspring. This was discovered for the first time in a new study that was carried out at the University of Haifa and published in the journal Developmental Psychology in a Special Section on “The Interplay of Biology and the Environment Broadly Defined.”
The effects of trauma that a mother experienced in the course of pregnancy are known from earlier research, but until now the influence of adversity before conception has not been examined. The present research, carried out by Prof. Micah Leshem and Alice Shachar-Dadon of the University of Haifa and Prof. Jay Schulkin of the Georgetown University School of Medicine, is the first to examine these influences.
The researchers chose to investigate rats, as social mammals with cerebral activity that is similar in many ways to that of humans. The present study 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. When the rats’ offspring reached maturity (at 60 days), the researchers examined their emotional behavior - anxiety and depression - and social behavior.
The main finding revealed that trauma experienced by the females prior to conception had varied effects on the offspring. According to Prof. Leshem, these effects varied between groups and between male and female offspring; but their behavior 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. “Everyone knows that smoking harms the fetus and therefore a mother must not smoke during pregnancy. 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. We should be prepared for analogous effects in humans: for example, in children born to mothers who may have been exposed to war well before becoming pregnant,” Prof. Leshem concluded.