Avoid Excess Pregnancy Weight to Protect Your Unborn Baby’s Brain

Are you expecting or trying to get pregnant? Keep your weight at a health level. Obesity during pregnancy has health risks and may harm a developing baby’s brain.

If you hope to get pregnant or are expecting, you likely know that weight gain is a normal part of pregnancy. Gaining too much weight, or being significantly overweight to begin with, however, has several health risks for you and your baby.

In fact, obesity during pregnancy could hinder the development of your baby’s brain as early as the second trimester, potentially raising his or her risk of developing attention-deficit hyperactivity disorder (ADHD) and possibly autism. 

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Obesity in pregnancy carries risks

The majority of Americans are now overweight, and nearly half are obese, according to the Centers for Disease Control and Prevention. Being significantly overweight when you are pregnant increases the odds of several health problems for both you and your baby.

For example, gaining more than the recommended amount of pregnancy weight, or being obese when you become pregnant, is associated with having a baby who is born too large, which can lead to delivery complications, including a need for a cesarean delivery.

A baby born to an obese mom can also develop obesity during childhood.

If you are overweight, you are more likely to have gestational diabetes, a form of diabetes that occurs only during pregnancy. Studies also link excess weight during pregnancy with the development of preeclampsia (extremely high blood pressure and sometimes kidney and liver damage), a condition potentially life-threatening to both you and your unborn child.

How a mom’s excess weight may affect an unborn baby’s brain

Previous studies have revealed a link between obesity during pregnancy and brain development, but they looked at cognitive function in children after birth. Research, published in the Journal of Child Psychology and Psychiatry, however, documented changes in fetal brain activity in the womb (as early as six months into pregnancy) to investigate the earliest possible negative effects of excess maternal weight on a developing baby’s brain.

The researchers recruited 109 women who were between six and nine months pregnant. The women had body mass indexes (BMIs, a measure of body fat based on height and weight) ranging from 25 to 47. According to the National Institutes of Health, women with BMIs of 25 or more are considered overweight; a BMI of 30 or higher indicates obesity.

Using MRI imaging, the researchers measured and mapped fetal brain activity, specifically the communication between large numbers of neurons (brain cells) clustered together in different parts of the brain.

In all, the researchers investigated 197 groups of metabolically active nerve cells in the fetal brain. Then, using millions of computations, they divided those groups into 16 meaningful subgroups of connections between groups of neurons. Next, the researachers looked for associations between the study volunteers’ weight and how the groups of neurons communicated with each other.

The results showed a statistically strong link between pregnant women who were obese and changes in two brain areas of their unborn babies — the prefrontal cortex and anterior insula. Those regions are crucial for decision-making and behavior. Previous brain research has shown disruption in brain activity in those parts of the brain links to ADHD, autism, and overeating.

“Our findings affirm that a mother’s obesity may play a role in fetal brain development, which might explain some of the cognitive and metabolic health concerns seen in children born to mothers with higher BMI,” said researcher and NYU associate professor of child and adolescent psychiatry Moriah Thomason, PhD.

Avoid excess weight during your pregnancy

If you are overweight and trying to conceive, you should work with your doctor to get your weight under control. If you are already pregnant and overweight, you should recognize the importance of following your doctor’s nutrition advice and work to avoid gaining more weight.

The investigators caution their research wasn’t designed to draw a direct line between fetal brain activity changes associated with overweight moms-to-be and any thinking or behavioral problems in toddlers or older children.

The NYU team does, however, plan to follow the study participants over time to see if children who showed brain activity changes before birth develop ADHD, behavioral problems, and other health problems.

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