Next time you run into your pregnant friend, do not hesitate to startle her. A new study conducted by Dr. Avi Avital from the Faculty of Medicine at the Technion in Haifa, Israel, and “Ha’Emek” Hospital in Afula, indicates that minor scares don’t harm mother and baby, on the contrary.
Maternal stress during pregnancy most likely positively affects the ability of the offspring to cope with states of mental and physical distress in maturity. This counter-intuitive idea is based on studies conducted on rats, but is also supported by previous findings on humans.
Dr. Avital initially exposed pregnant rats to stressful stimuli and later on checked how their offspring coped with pressure in maturity. It turned out that rats were born to mothers that were calm during pregnancy responded to pressure with high levels of corticosterone – a hormone which is associated with stress. On the other hand, rats that experienced stress as fetuses kept normal levels of corticosterone in maturity, even in stressful situations.
The hormone levels was not the only difference between the groups of rats. The reaction to stress in the mature rats also differed. The rats that first experienced distress while in their mothers’ womb showed restrained behavior in stressful conditions, while rats that first encountered pressure in maturity responded by making body movements which indicated distress.
Rats that were more “easy-going” due to exposure to stress in pregnancy often demonstrated survival instincts, even those demanding more cognitive investment. Another study found that their attentiveness did not decrease while being under pressure, compared to others that were not exposed to stress as fetuses.
The assumption is that pressure on the mother during pregnancy causes the secretion of substances that “imply” to the fetus that life outside the womb is tough and will require determination to deal with reality.
However, stress during early stages of the rats’ lives did not improve their conditions, on the contrary. Rats exposed to stress pre-adolescence suffered even more from distress in subsequent years.