The Myth of Normal 117

Beyond brain substance levels, there is evidence suggesting that maternal mind states during pregnancy and postpartum shape the very structure of the infant’s developing brain. In one study, nursing professor Dr. Nicole Letourneau, Canada research chair in parent-infant mental health at the University of Calgary, and her colleagues found that the child’s gray matter, the cerebral cortex, was thinner on MRI scanning of the brains of preschool children whose mothers had suffered depression in the middle three months of pregnancy. As they point out, their brain-scan findings may presage later problems such as depression, anxiety, impaired impulse control, and attention difficulties in the child.[5] Postpartum depression had similar effects, indicating that there are certain critical periods in development, both before birth and after, during which the young human is particularly vulnerable to the environment. Such findings align with those of multiple other studies, which point to maternal-stress impacts on such brain structures as, for instance, the fear- and emotion-processing amygdala[6] and on neurological conditions such as autism.[7] Other findings suggest strongly that many adult health challenges— everything from mental health disorders to hypertension, heart disease to diabetes, immune dysfunction to inflammation, and poor glucose metabolism to hormonal imbalance—are made more likely by intrauterine stress.[8] Among researchers there is a “universal consensus,” to cite a major review paper, that what are called the developmental origins of adult disease begin in the womb.[9] Remember telomeres, the chromosomal markers of health and aging? These structures were shown to be shorter—that is, more prematurely aged— in twenty-five-year-old adults whose mothers had undergone major stress during pregnancy.[10] We also know from our section on epigenetics that a mom’s high stress levels during gestation can negatively influence the genetic functioning of the offspring, potentially impairing his lifelong stressresponse capacities. Such effects have been shown to last well into midlife. [11] Maternal stress during pregnancy has even been correlated with a poor makeup of the infant’s gut microbial flora—a less healthy mix of bacteria—