Pregnancy Brain: Myth Or Fact?

Pregnancy Brain

An inability to concentrate, a tendency to forget things, and difficulty making decisions—these are just a few of the symptoms that pregnant women have associated with a state of mind referred to as “pregnancy brain.”

While many women report increased forgetfulness and lack of focus during pregnancy, science has not always agreed that pregnancy brain really exists. One 2014 study concluded that women’s mental abilities do not suffer during pregnancy but a 2016 study found that there may be scientific clues to those foggy feelings.

It’s all in your mind

Studies into the existence of pregnancy brain fall into two categories: studies that ask pregnant women how they feel and studies that attempt to objectively measure mental capability.

A 2014 study by Brigham Young University tested for capability. The study compared 21 pregnant women, when they were in the third trimester and then again approximately three months postpartum, with matched controls over the same time period. The researchers found that all the women performed equally well on the tests, although without seeing the results, the pregnant women and new moms were sure they did not do that well.

The study concluded that women experienced the symptoms they described as pregnancy brain primarily because they assumed it was going to happen.

Pregnant and postpartum subjects lacked confidence in their answers, said the researchers, because the women expected to be mentally impaired by their pregnancy.

Confirming whether pregnancy brain exists may be more complicated than getting women to answer test questions. A previous study, in 2008, found that pregnant women did as well on tests as women who were not pregnant, but that pregnant women had more difficulty performing hypothetical real-life tasks.

Several factors may contribute to a woman feeling she is not thinking as clearly during pregnancy. Rising hormone levels, insufficient sleep, and added stress can contribute to forgetfulness and a sense of fogginess, while structural changes in the brain may actually be altering the way a pregnant woman’s brain works.

Explanations for Pregnancy Brain

There are several physical and emotional reasons that women might have difficulty focusing during pregnancy. The first is hormones. Progesterone levels soar 20 to 40 times their normal levels during the first trimester and often have a sedative effect. Rising progesterone levels can lead to sleepiness during the day or it may be hard to sleep well at night. Disrupted sleep cycles can result in that not-quite-awake feeling.

Also, being pregnant means there’s more to think about and plan for, some of it wonderful and some of it stressful. With so many important decisions to make, an expectant mom is more likely to forget something. Being both tired and stressed can lead to forgetfulness.

Another very important factor may be the remarkable physical changes that take place in a woman’s brain during pregnancy.

A study published in November 2016 described significant physical changes that might cause a woman to feel as if she is not thinking as clearly. The study published in  Nature Neuroscience showed that pregnancy changes brain structure. During pregnancy, the gray matter in specific regions of a woman’s brain actually shrinks. While a loss of gray matter might sound alarming, these changes actually help a woman’s brain adapt to motherhood and respond to an infant’s needs. The part of the brain most affected is the part that interprets social signals and empathizes with others.

The study, conducted at Leiden University in the Netherlands, scanned the brains of 45 women and 24 men over a period of five years. Parents were scanned both before and after a child was born.  A significant shrinkage was noted in the brains of pregnant women, with gray matter remaining the same size for up to two years after a child’s birth. Researchers reported no changes in the men’s gray matter or in that of the women who did not become pregnant.

A similar decrease in gray matter happens to both genders during late adolescence and is seen as a sign of maturation, because it also fine tunes the brain in preparation for adulthood.

Researchers in the 2016 study reported that the more pronounced the structural changes  were during pregnancy, the better the woman seemed to bond with her new infant.

Is pregnancy brain a myth? There’s definitely something going on in the brain of pregnant women that might make it difficult to focus. If shrinkage of the brain’s gray matter is at fault, then the fogginess and forgetfulness is for a good cause.

Joan MacDonald
Joan Vos MacDonald has written about health and fitness for newspapers, magazines and websites. She is a member of the National Association of Science Writers and the author of two books on health-related topics, "Tobacco and Nicotine Dangers," for young adults, and "High Fit Home," a design book about fitness and architecture. She lives in upstate New York near her children and grandchildren.

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