How Pregnancy and Motherhood Affect a Woman’s Brain
We spoke to the experts
When a woman becomes pregnant, many questions enter her brain except, perhaps, the one that pertains directly to it: Does pregnancy and motherhood affect a woman’s brain?
“Yes,” says Liisa Galea, a professor of psychology and director of the graduate program in neuroscience at The Women’s Health Research Institute at the University of British Columbia. “Exercise affects the brain. Diet affects the brain. Of course, having a baby is going to affect your brain.”
And that’s a good thing, she says. The changes in a woman’s brain during pregnancy ease her transition to motherhood by prepping her mind for bonding and vital maternal behavior.
“During pregnancy, a mother’s brain is primed for attachment — luckily!” she says. “Before I had my children, I was totally selfish. But the moment my baby was in my arms, all I could think about was him.”
Remember that crazy love you felt for your newborn? Yes, it was partly because he was the most amazing creature ever born — but it was also your body’s dramatic increase in oxytocin, prolactin and progesterone prodding your brain to adapt.
Robert Bridges, a professor of neuroscience and reproductive biology and behavioral neuroendocrinology at Tufts University, has been studying the biological basis of maternal behavior since 1974, focusing his research on the endocrine system and brain. His animal studies reveal that all animals have the capacity to respond to infants, but that “the physiological changes in the brain during pregnancy especially prime an expectant female for motherhood,” he says.
Estrogen, progesterone and prolactin increase “as much as five hundredfold” Galea says. They work not only to provide for the developing fetus, but also to signal the maternal brain to respond.
Bridges emphasizes the pre-optic area of the expectant mother’s brain, which increases production of natural opioids during gestation, then decreases production after delivery.
“The opioid system helps manage pain, but excessive opioid production may also be disruptive to maternal care,” he says, explaining its rise and fall. Bridges has observed a connection between higher levels of dopamine following birth and the receptiveness of the brain’s reward system, which is helpful in infant bonding, and says “oxytocin is also integral to mother-child bonding.”
One of his studies demonstrates the longer-term effect of these hormones, as well as what he calls a “shift in the brain.” In the study, females who had previously given birth displayed an increased facility in how their brain interpreted and responded to pregnancy hormones, compared with first-time mothers.
In addition to the flow of hormones affecting cognition, pregnancy induces structural changes in the brain in order to ease and direct hormone flow. Bridges says these changes occur primarily in the brain’s gray matter and medial pre-optic area, which is part of the hypothalamic-pituitary-adrenal axis and is related to stress response. Galea has reviewed studies that confirm these changes.
“Research shows that there is a general reduction in the amount of gray matter in a pregnant woman’s brain,” she says, referencing a 2016 study led by neuroscientist Elseline Hoekzema of Leiden University.
Gray matter is associated with effective executive function, which includes working memory, planning and problem solving. While its loss might sound alarming, the reduction in gray matter simply makes room for skills more vital to early motherhood.
“Don’t confuse more with better,” Galea says. “Sometimes less is better,” adding that the same study did not observe a reduction in cognitive function (e.g. memory), but did find that less gray matter was associated with a more effective mother-infant attachment.
Galea also points out that the loss in gray matter during pregnancy is temporary.
“It builds back up postpartum,” she says.
And studies indicate that within five years, woman who had children actually performed better than non-mothers on memory tests. “Not only does the gray matter regenerate — it is potentially stronger than ever,” she says.
While gray matter decreases to make way for nurturing, Bridges notes that the hypothalamic-pituitary-adrenal axis, which processes anxiety and fear, is more responsive during pregnancy and postpartum. This makes a woman more sensitive to hormone triggers and, thus, more sensitive to her baby’s needs.
“A certain increase in anxiety is good,” says Audrey Atkinson, a licensed clinical psychologist and owner of Balanced Mind Psychological Services in Davidson. “It encourages a new mother to be vigilant in feeding and caring for her infant, to be particularly sensitive to her baby’s cry and to be protective of the infant from outside threats.”
The helpful rush of hormones does not buoy a mother much beyond the first few months of parenting. That’s when the brain’s plasticity and reward system kick in. Dopamine, one of the hormones that increases postpartum, may help boost the plasticity of the brain’s neural systems.
“It may make the brain’s reward system more effective,” Bridges says, “allowing a mother’s brain to change and adapt with the needs of her child.”
Beyond age 2, “a parent’s behavior with her growing child will be powerfully influenced by the child’s behavior and temperament,” says Kirby Deater-Deckard, a developmental psychologist and professor of brain sciences at the University of Massachusetts Amherst, as well as director of the Healthy Development Initiative at the UMass Center in Springfield.
Deater-Deckard has found that a child’s behavior during parent-child interaction has a more profound effect on a mother’s parenting behavior in the moment than any other factor, including socioeconomic, familial or health-related issues. A mother’s brain is thus primed by pregnancy and childbirth to effectively adapt and change in response to each of her children.
Short-Term Side Effects
The heightened sensitivity in the brain brought on by pregnancy hormones and brain adjustments may make new mothers vulnerable to anxiety, depression and obsessive-compulsive disorder.
“An appropriate level of anxiety can morph from a motivating level into obsession,” Atkinson says, adding that postpartum depression, anxiety or OCD affects one out of seven new mothers, and that women “don’t realize that pregnancy hormones really amplify what they’ve experienced before.”
Amanda Harp, an assistant professor of psychology in the UNC Center for Women’s Mood Disorders, says a lot of her patients are naturally more anxious people who, up until pregnancy, have been able to manage it. “Some are just more sensitive to hormones,” she says, noting that studies are underway at the center to look at whether there is a specific phenotype for hormone-sensitive women.
Harp notes that depression is particularly tricky in pregnancy and early motherhood because it is difficult for a new mother to find time to seek help. She says she hopes increased access to telemedicine will serve as a boon for addressing this problem. Atkinson is also hopeful, citing improved publicity and acceptability of this issue.
Long-Term Side Effects
It makes sense that such dramatic changes to the brain could have long-term effects, and there are studies being done that may make a positive impact on addressing these issues.
In a current study of middle-aged women, Galea is finding health differences between women who have been pregnant versus those who have not.
“We are noticing differences in disease susceptibility,” she says. “For example, women who have had multiple births may be more vulnerable to Alzheimer’s. At the same time, motherhood appears to provide some protection against breast and ovarian cancer. We are also seeing markedly different reactions to hormone therapy.”
These distinctions are not better or worse, she points out — just different. “The more we know about these differences, the better we will be able to treat individuals,” she says. “This is incredibly important research.”
Caitlin Wheeler is a Parenting Media Association award-winning writer who lives in Durham.