Attention pregnant mothers: Besides giving up caffeine and alcohol, suffering from morning sickness, making sure you don’t gain too much weight, and taking prenatal vitamins, new research says you have to remain calm during your pregnancy. That’s right. A new study has shown that prenatal maternal stress can be harmful to your baby. I know what you’re thinking: “Pregnancy–as joyful as it can be–is also the cause of a lot of stress. You gain weight, you have difficulty sleeping, your partner may not find you as alluring. And now researchers are telling me that I have to remain calm during pregnancy too?  I need a drink. Oh, right, I can’t drink because I’m pregnant.”

Researchers have long known maternal stress is harmful to animals. Yet there has not been a lot of research on this topic in humans. So a team of Canadian researchers (Leung et al.) looked at the effects of maternal stress in humans by studying 84 mothers and their newborns at two days and 10 months after birth. They found there was a direct relationship between prenatal maternal stress and children’s cortisol reactivity, a measure of the body’s physiological reaction to stress. In other words, mothers who were more stressed while pregnant had infants who tended to be more stressed as well.

Some stress is healthy and necessary to trigger the development of adaptive social and emotional skills.  But my own research and that of others’ has shown that chronically high cortisol levels, or being highly reactive to stressors, can have negative health consequences over the long term.

The take away lesson is that we can now say with more confidence that managing stress while pregnant is important, along with not smoking, not gaining too much weight, and eating healthy.  Stress reduction during pregnancy is a win-win situation for mothers, infants, and the family as a whole.

So take a deep breath and relax–together.  If you’ve used Family Foundations to help prepare for parenthood, then you and your partner should already know a few ways to relax.  And in fact, that ability to relax and manage stress just might be why Family Foundations kids have better sleep, attention, self-soothing capacity, and social adjustment—as well as lower levels of emotional and behavioral problems—compared with other kids.  You can read more about our research here.