© Getty Images

Forgetfulness. Lack of focus. Occasional foggy-mindedness. Ask a new or expectant mom if “pregnancy brain” is real, and most will laugh (or groan) and say there’s no doubt about it. But when researchers have gone looking for proof of these cognitive hiccups, the results have been mixed.

A talked-about 2014 study from Brigham Young University found no memory or attention issues among pregnant or postpartum women compared to matched controls. “Objectively, the pregnant and postpartum women and non-pregnant women performed equally well in the cognitive tests,” says Dr. Michael Larson, a clinical neuropsychologist and coauthor of the BYU study.

But subjectively—that is, when women were asked to rate their own performance on the tests—the pregnant and postpartum women felt they’d done poorly compared to their non-pregnant counterparts.

“There’s this cultural stereotype that women are supposed to suffer cognitively during or after pregnancy,” Larson says. Belief in this stereotype could hamper some women’s confidence in their cerebral acuity even though their brains are working just fine, he says.

But the BYU study is not the final word on the subject of “pregnancy brain.” Importantly, Larson says all the women in his experiment were tested “in ideal circumstances.” That is, he and his colleagues controlled for sleep, stress and other factors that could disproportionately affect pregnant and postpartum women outside the lab.

“There’s likely a disconnect between real-world functioning and ideal-experiment functioning,” he says. “But our goal was to see if women’s cognitive abilities changed during or following pregnancy, and we didn’t find evidence of that.”

In the “real world,” there’s little doubt pregnant and postpartum women have to contend with factors that may affect their thinking, says Dr. Louanne Brizendine, a neuropsychiatrist at the University of California, San Francisco, and author of The Female Brain.

During the first few months of pregnancy, a woman’s progEsterone levels soar to 20, 30 or even 40 times their normal levels, Brizendine says. This hormone is a potent sedative, and its surge explains why some women may feel especially worn out during the early stages of pregnancy. (The BYU study only involved women in their third trimester.)

“This progesterone surge doesn’t mean you lose smarts or brain function,” Brizendine says. “It’s just that you feel sleepy a lot of the time.”

While a woman’s brain and body become accustomed to the uptick in progesterone as her pregnancy progresses, other hormonal fluctuations—as well as body changes and discomfort—often lead to restive sleep. So does having to deal with a newborn at all hours of the night.

“It’s not reasonable to think that a woman could go through all the hormonal and physical changes of pregnancy and not have it affect her brain just as it affects her body,” Brizendine says. At the same time—and as the BYU study underscores—a pregnant woman’s brain doesn’t become somehow deficient or less capable, she says.

All of this can start to seem like semantics. But because some might use “pregnancy brain” as an excuse to justify workplace practices that discriminate against women, the semantics can prove important.

“Modern fathers live and breathe all of the pregnancy stages along with their partners, feel much of the same stress and distraction, and are often just as involved in post-natal care and middle-of-the-night feedings,” Brizendine adds. In the real world, dads are often as likely as moms to grapple with poor sleep and preoccupying thoughts—though they don’t suffer from the stereotypes Larson mentioned.

Expectant couples aside, few of us walk into work fully rested and unburdened by stress or distraction. Even hunger can mess with our ability to think clearly. So while researchers keep unpacking “pregnancy brain” and its sociopolitical implications, it’s safe to say that all people—including pregnant women—occasionally have to work with somewhat encumbered brains.