A new study has revealed that reproductive hormones may prepare a woman's brain for the demands of motherhood by helping her becomes less worked up by stress and more in tune to her baby's needs.
Although the hypothesis remains untested, psychologist Laura M. Glynn of Chapman University surmised that this might be why moms wake up when the baby stirs while dads snore on.
Other studies confirm the truth in a common complaint of pregnant women: "Mommy Brain," or impaired memory before and after birth.
At no other time in a woman's life does she experience such massive hormonal fluctuations as during pregnancy.
The article reviews research that refines earlier findings on the effects of the prenatal environment on the baby. For instance, evidence is accumulating to show that it is not prenatal adversity on its own-say, maternal malnourishment or depression-that presents risks for a baby.
Congruity between life in utero and life on the outside may matter more. A foetus whose mother is malnourished adapts to scarcity and will cope better with a dearth of food once it's born-but could become obese if it eats normally.
Timing is critical too: maternal anxiety early in gestation takes a toll on the baby's cognitive development; the same high levels of stress hormones late in pregnancy enhance it.
Just as mom permanently affects her foetus, new science suggests that the foetus does the same for mom. Foetal movement, even when the mother is unaware of it, raises her heart rate and her skin conductivity, signals of emotion-and perhaps of pre-natal preparation for mother-child bonding.
Foetal cells pass through the placenta into the mother's bloodstream.
"It's exciting to think about whether those cells are attracted to certain regions in the brain" that may be involved in optimizing maternal behaviour, said Glynn.
Glynn cautions that most research on the maternal brain has been conducted with rodents, whose pregnancies differ enormously from women's; more research on human mothers is needed.
The study has been published in Current Directions in Psychological Science, a journal published by the Association for Psychological Science.