Take it easy: keeping stress levels low during pregnancy is important for a child’s long-term well being.Pregnancy can be a worrying time for many women, but now a new study by Israeli researchers shows that stress during these vital nine months can lead to slower development, learning and attention difficulties, anxiety, depressive symptoms, and possibly even autism in a child.

Stress during pregnancy has long been recognized as a cause of developmental and emotional problems, but objective measurement of it has been impossible in humans since evidence is based largely on anecdotal recollections, and is strongly influenced by genetics and other factors.

Prof. Marta Weinstock-Rosin of the Hebrew University of Jerusalem, took an alternative route to try to uncover the facts about this relationship. In experimental work with laboratory rats she was able to demonstrate conclusively that there is a definite link.

“There is an enormous advantage in working with rats since we are able to eliminate the genetic and subjective element,” explains Weinstock-Rosen.

Working with a team of researchers, Weinstock-Rosen, from the Hebrew University’s school of pharmacy, was able to compare the behavior of the offspring of stressed rat mothers with those whose mothers were not stressed. They also compared the results of administering various types of stress at different periods during the gestation process to see which period is the most sensitive for the production of different behavioral alterations.

Through laboratory experiments, Weinstock-Rosin discovered that when rat mothers were subject to stressful situations such as irritating sounds at alternating times, their offspring were later shown to have impaired learning and memory abilities, less capacity to cope with adverse situations (such as food deprivation), and symptoms of anxiety and depressive-like behavior, compared to those rats in control groups that were born to unstressed mothers.

All of these symptoms are similar to impairments observed in children born to mothers who were stressed in pregnancy, she points out.

Keep cortisol levels low

Further experiments by Weinstock-Rosin and her students have shown the crucial effect of excessive levels of the hormone cortisol that is released by the adrenal gland during stress and reaches the fetal brain during critical stages of brain development.

Under normal conditions, this hormone has a beneficial function in supplying instant energy, but it has to be in small amounts and for a short period of time. Under conditions of excessive stress, however, the large amount of this hormone reaching the fetal brain can cause structural and functional changes. In humans, above-normal levels of cortisol can also stimulate the release of another hormone from the placenta that will cause premature birth, another factor that can affect normal development.

Weinstock-Rosin’s work, along with that of colleagues from Israel, the UK and elsewhere, will be presented at an international conference, “Long Term Consequences of Early Life Stress,” which she is co-chairing with Dr. Vivette Glover of the Imperial College, London. The event will be held in Jerusalem at the end of October.

Weinstock-Rosin says that further experimental work is required in order to study other possible effects resulting from raised hormonal levels on the offspring.

In the meantime, however, one thing is clear: keeping pregnancy as stress free as possible is not only a good prescription for a healthy nine months, but also for healthy children as well.