Mother Nature Knows Best | curiousSCIENCEwriters

In Brief:

Stress can be helpful or harmful.
High stress levels during pregnancy can cause the premature birth of babies with life-threatening health problems.
Cortisol is a hormone that helps regulate stress.
High cortisol levels in pregnant red squirrels help newborns adapt to life-threatening conditions.

[“Gwen in the isolette”, (Unedited). License: CC BY-NC-ND 2.0]

Baby Alex arrived 2 ½ months early, unresponsive and not breathing. Following emergency living-saving surgery, the premie, who weighed in at 2 lbs 5 oz, began fighting to survive (Bird, 2010). Only time would tell if he would develop lifelong disabilities and behavioral problems (Dimes, 2014) as a result of arriving so early. A pregnant woman who experiences high levels of stress that last a long time is at-risk for having a premature baby, who may experience a wide range of development delays and health problems if he or she survives. Researchers studying red squirrels are investigating the role of maternal cortisol, a stress hormone, in producing babies that are bigger and better able to survive.

So what happens when we are stressed?
Although a small amount of stress can help us survive, long-term stress can have very harmful effects on the body. Studies show that chronic stress can weaken the immune system, increasing susceptibility to infection. It can also lead to serious problems, such as high blood pressure, anxiety and depression. Such health problems can put both the expectant mother and her unborn child at-risk. (“Stress Management-Effects of Stress,” 2013) Studies in mice have shown that a high stress pregnancy can have detrimental effects on a newborn’s brain development.

Cortisol is a hormone that helps regulate stress. In a dangerous situation, your body produces more cortisol as you prepare to run away fast or stay and fight for your life. Being in a high state of alert at such times is good. But having high levels of cortisol in your blood for long periods of time can lead to chronic stress, which has many negative effects, such as lower immunity, slower wound healing, higher blood pressure and impaired cognition.

Surprisingly, having high levels of cortisol is not always bad, especially if you are a North American red squirrel.

A team of scientists led by Ben Dantzer studying the impact of population density and competition for food on survival found that pregnant red squirrels in a more crowded forest had higher cortisol levels and produced babies that grew faster. They found that an excess of maternal cortisol in red squirrels helped offspring grow an astonishing 41% faster than babies of mothers with a normal level of the hormone. (Chung, 2013).

In humans, it seems to be all about timing. Davis and Sandman are looking at the impact of maternal cortisol on an infant’s development during the first year of life. Their studies suggest that exposure to a higher level of cortisol towards the end of pregnancy is associated with a child’s accelerated development over the first year and higher scores on the Bayley Scales of Infant Development at 12 months (Davis, Sandman 2010). These studies may not provide all the answers, but they offer important insight into how mothers labor to ensure the survival of the fittest.

Works Cited

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