Interesting Psychology Team
3. Avoid too much stress
It was not a good idea to be in Quebec and pregnant around January 4, 1998. For more than 80 hours, freezing rain and drizzle fell relentlessly all over eastern Canada—immediately followed by a steep drop in surface temperature. This meteorological one-two punch turned eastern Canada into ice hell.
Under the weight of the freeze, more than a thousand towering metal power-line structures toppled like dominoes. Tunnels collapsed. Thirty people died. A state of emergency was soon declared; the army was called up. Even so, thousands of residents were without power for weeks. And in freezing temperatures.
If you were pregnant and could not get to a hospital for your regular checkups—God forbid if you went into labor—you were stressed out of your mind. And so, it turned out, was your infant. The effects of that storm could be seen on their brains years later.
How do we know that? A group of researchers decided to study the effects of this natural disaster on babies in the womb—then follow the children as they grew older and entered the Canadian education system. The result is scary. By the time these “ice storm” children were 5, their behaviors differed markedly from children whose mothers hadn’t experienced the storm. Their verbal IQs and language development appeared stunted, even when the parents education, occupation, and income were taken into account. Was the mother’s stress the culprit? The answer turned out to be yes.
Maternal stress can profoundly influence prenatal development. We didn’t used to think so. For a while, we weren’t even sure if mom’s stress hormones could reach her baby. But they do, and that has long-lasting behavioral consequences, especially if the woman is stressed, severely or chronically or both, in those magic, hypersensitive last months of pregnancy. What kind of consequences?
If you are severely stressed during pregnancy:
• It can change the temperament of your child: Infants become more irritable, less consolable.
• It can lower your baby’s IQ: The average decline is about 8 points in certain mental and motor inventories measured in a baby’s first year of life. Using David Wechsler’s 1944 schema, that spread can be the difference between “average IQ” and “bright normal”.
• It can inhibit your baby’s future motor skills, attentional states, and ability to concentrate, differences still observable at age 6. It can damage your baby’s stress-response system.
• Stress can even shrink the size of your baby’s brain.
A review of more than 100 studies in various economically developed countries confirm that these powerful, negative effects on prenatal brain development are cross-cultural. David Laplante, lead author of the ice-storm study, said in a somewhat understated fashion:
“We suspect that exposure to high levels of stress may have altered fetal neurodevelopment, thereby influencing the expression of the children’s neurobehavioral abilities in early childhood.”
Is this stressing you out? Luckily, not all stresses are created equal. Moderate stress in small amounts, the type most women feel in a typical pregnancy, actually appears to be good for infants. (Stress tends to get people moving, and we think that enriches the baby’s environment.) The womb is a surprisingly hearty structure, and both it and its tiny passenger are well-equipped to ride out the typical stressors of pregnancy. It is just not prepared for a sustained assault. So, how can you tell the brain-damaging stress from the typical, benign, even mildly positive stress?
3 toxic types of stress
Researchers have isolated three toxic types. Their common characteristic: that you feel out of control over the bad stuff coming at you. As stress moves from moderate to severe, and from acute to chronic, this loss of control turns catastrophic and begins to affect baby. Here are the bad types of stress:
• Too frequent. Chronic, unrelenting stress during pregnancy hurts baby brain development. The stress doesn’t necessarily have to be severe. The poison is sustained, long-term exposure to stressors that you perceive are out of your control. These can include an overly demanding job, chronic illness, lack of social support, and poverty.
• Too severe. A truly severe, tough event during pregnancy can hurt baby brain development. It doesn’t have to be an ice storm. Such an event often involves a relationship: marital separation, divorce, the death of a loved one (especially the husband). Severe stress can also include the loss of a job or a criminal assault such as rape. The key issue, once again, is a loss of control.
• Too much for you. Mental-health professionals have known for decades that some people are more sensitive than others to stressful events. If you have a tendency to be stressed all the time, so will your womb. We have increasing evidence that part of this stress sensitivity is genetic. Women under such a biological dictatorship will need to keep stress to a minimum during pregnancy.
Rats! Dropped ‘em again!
Lots of research has gone into trying to understand how maternal stress affects brain development. And we have begun to answer this question at the most intimate level possible: the level of cell and molecule. For this progress we mostly can thank the klutzy researcher Hans Selye. He is the founder of the modern concept of stress. As a young scientist, Selye would grind up “endocrine extracts”, which presumably contained active stress hormones, and inject them into rats to see what the rats would do. He was not good at it.
His lab technique, to put it charitably, was horrible. He often dropped the poor lab animals he was attempting to inject. He had to chase them around with a broom, trying to get them back into their cages. Not surprisingly, the rats became anxious in his presence. Selye observed that he could create this physiological response just by showing up. His main job was to inject some animals with endocrine extract and others, in the control group, with saline. But he was perplexed to discover that both were getting ulcers, losing sleep, and becoming more susceptible to infectious diseases.
After many observations, he concluded that anxiety was producing the effect, a concept surprisingly new at the time. If the rats couldn’t remove the source of anxiety or cope with it once it arrived, he found, it could lead to disease and other consequences. To describe the phenomenon, Selye eventually coined the term “stress.”
Selye’s insight led to that rarest of all findings: the link between visible behaviors and invisible molecular processes. Selye’s work gave the research community permission to investigate how stressful perceptions could influence biological tissues, including brain development. We know a lot about how stress hormones affect growing neural tissues, including a baby’s, thanks to this pioneering insight. Though most of the research was done on rats, many of the same key processes have been found in humans, too.
The important stress hormone is cortisol. It’s the star player in a team of nasty molecules called glucocorticoids. These hormones control many of our most familiar stress responses, from making our hearts race like NASCAR autos to a sudden urge to pee and poop. Glucocorticoids are so powerful, the brain has developed a natural “braking” system to turn them off as soon as the stress has passed. A pea-sized piece of neural real estate in the middle of the brain, called the hypothalamus, controls the release and braking of these hormones.
Bull’s-eye: Baby’s stress-response system
A woman’s stress hormones affect her baby by slipping through the placenta and entering the baby’s brain, like cruise missiles programmed to hit two targets. This is the basis of the Brain Rule: Stressed mom, stressed baby.
The first target is the baby’s limbic system, an area profoundly involved in emotional regulation and memory. This region develops more slowly in the presence of excess hormone, one of the reasons we think baby cognition is damaged if mom is severely or chronically stressed.
The second target is that braking system I mentioned, the one that’s supposed to rein in glucocorticoid levels after the stress has passed. Excess hormone from mom can mean baby has a difficult time turning off her own stress hormone system. Her brain becomes marinated in glucocorticoids whose concentrations are no longer easily controllable.
The baby can carry this damaged stress-response system into adulthood. The child may have a difficult time putting on the brakes whenever she gets stressed out; elevated levels of glucocorticoids thus become a regular part of her life. If she eventually gets pregnant, she bathes her developing infant with the excess toxic stuff.
The fetus develops a partially confused hypothalamus, pumping out more glucocorticoids, and the next-generation brain shrinks further. The vicious cycle continues. Excessive stress is contagious: You can get it from your kids, and you can give it to them, too.
Take back control
Clearly, too much stress is not good for pregnant women or their babies. For optimal development of your baby’s brain, you will want to exist in a less-stressed environment, especially in the last few months of pregnancy. You can’t completely upend your life, of course, which could be stressful on its own.
But you can reduce your stress, with your spouse’s tender loving care. We’ll say much more about that in the next chapter. You can also begin identifying the areas in your life where you feel out of control, then deliberately form strategies that will allow you to take back control.
In some cases, that means exiting the situation that is causing the stress. A temporary helping of courage will translate to a lifetime of benefit for your baby’s brain.
There are plenty of ways to actively practice general stress relief, too. At www.brainrules.net,we’ve listed a number of techniques known from the research literature to reduce stress. A big one is exercise, which has so many benefits that it is the subject of our fourth and final balancing act.
