The authors conducted a review of literature in the Current Directions in Psychological Science
, a journal published by the Association for Psychological Science
According to the authors
, pregnancy represents a period of massive hormonal fluctuations and there are growing indications that reproductive hormones may help prepare a woman's brain for the responsibilities of motherhood. This observation led to the hypothesis that reproductive hormones of pregnancy help to adapt a woman to her baby's specific needs. According to Glynn, her hypothesis may explain why mothers wake up when their baby stirs while the father sleeps on. Glynn also suggests that a "cost" of the unique cognitive and emotional adaptations in pregnancy may be the common complaint of impaired memory before and after birth, popularly called "Mommy Brain." The benefit which appears to outweigh the cost, according to Glynn, is a "more sensitive and effective mother."
In their review of recent research that refine earlier work on the effects of prenatal environment on the baby, the authors point out that evidence is emerging showing that it is not prenatal adversity such as maternal malnourishment or depression that present risks to baby. The authors say there is evidence that congruity between life in utero and life outside may be a more important factor. They also point to evidence that maternal anxiety in the early stages of pregnancy adversely affect the baby's cognitive development, while similar high levels of stress hormone in late pregnancy enhance cognitive development.
The authors say that it is not only the mother whose pregnancy states affect the baby. The baby in the uterus also exerts significant effects on the mother's states. They cite evidence that fetal movement, even when the mother is unaware of it, raises her heart rate and skin conductivity, these being signals of emotion. Fetal cells also pass through the placenta into the mother's bloodstream. According to Glynn: “It’s exciting to think about whether those cells are attracted to certain regions in the brain that may be involved in optimizing maternal behavior."
A limitation of current research on maternal brain is that most were conducted using rodents whose pregnancies are very different for human pregnancies. The authors say there is need for more research on human mothers. They expressed the optimism that "...a more comprehensive picture of the persisting brain changes wrought by pregnancy will yield interventions to help at-risk mothers do better by their babies and themselves."
reported that psychologists say new developments in neuroscience show that letting babies "cry it out" is dangerous for their longterm health. Caregivers who respond promptly to a baby's need are more likely to have children who are independent. Major changes to a woman's brain induced by her pregnancy reproductive hormones may therefore be important for making mothers responsive to their babies' need for attention.