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Researchers recommend pregnant women eat a healthy, well-rounded diet. Getty Images
  • Researchers are learning more about how a pregnant woman’s diet can affect the chance of her child developing allergies.
  • Additionally, researchers have found that cesarean delivery may increase the risk of allergies in infants, compared to vaginal delivery.
  • Researchers say women should try to eat a well-rounded diet and stay healthy but not be overly worried about the risks.

Experts have long known that when a woman is pregnant, what she eats and what she’s exposed to can have an effect on the fetus.

Now, they’re learning how a pregnant woman’s diet, and even how she delivers her child, could affect the infant’s risk of developing allergies.

According to two new studies, how a woman eats while she’s pregnant, how she delivers, and how she feeds her baby can all have an impact on the child’s risk for developing allergies.

The research was presented at the American College of Allergy, Asthma, and Immunology (ACAAI) annual meeting.

The first study looked at data from more than 158,000 children. The researchers examined children with food allergy, eczema, asthma, and hay fever. Then, they looked at how the children were delivered and whether they were exclusively breastfed.

“We found vaginal delivery was associated with a reduced rate of development of allergic conditions,” Dr. David Hill, an allergist and lead author, said in a statement.

“While a mother can’t always control the way her baby is delivered, exclusive or supplemental breastfeeding may be helpful in reducing the rate of onset and overall burden of allergies in children,” Hill added.

The second study aimed to see if a link existed between how mothers ate during pregnancy, their history of allergic disease, and the child’s development of eczema and food allergy.

Carina Venter, PhD, RD, study presenter, tracked what 1,315 pregnant women ate during pregnancy, while noting their history of allergies.

Kids who were more likely to develop eczema and/or food allergies were born to mothers with poor diet diversity who had a history of allergic disease. In fact, 33 percent of children developed allergies by the age of 2 if their mothers had poor diet diversity and a history of allergic disease.

And 21 percent of children whose mothers ate a more varied diet while pregnant, regardless of whether or not they had a history of allergic disease, went on to develop eczema and/or food allergy by the time they were 2.

Pregnant women — especially those with allergies — need to be aware that their diet can affect their child’s chances of having eczema and/or food allergies, the authors reported.

Venter told Healthline that her study “really gives us an indication that everything may start in the womb.” She said it suggests that there may be dietary information that doctors could suggest to mothers in order to prevent food allergies or eczema in their children. More research, including a randomized controlled trial, would be needed to drive specific recommendations.

“More information is definitely needed before a cause and effect relationship [between diet, delivery and/or infant feeding as it relates to allergy development] can be confirmed,” noted Dr. Jennifer Savitski, chair of the OB-GYN department at Cleveland Clinic Akron General.

Though the studies may be making headlines, the findings aren’t anything new, according to Stacey Galowitz, DO, an allergy specialist from New Jersey.

We still don’t know for certain how specific foods in the maternal diet, or lack thereof, have an impact on allergy development. We also don’t know what parts of a mother’s microbiome affect an infant’s immune development.

“A number of convincing studies have supported the concept of a critical window of exposure to allergens early in infancy — and perhaps even in prenatal life — in the prevention of allergic diseases,” she told Healthline.

Alterations in maternal diets during pregnancy have been suggested as a way to limit the development of allergies, asthma, and atopic dermatitis.

Currently, there aren’t specific recommendations to definitively prevent allergies in their unborn child. But most experts support maintaining a well-balanced diet throughout pregnancy and lactation, as specific restrictions of key allergens haven’t been shown to prevent the future development of allergic disease in children, Galowitz noted.

“At the moment, I advise women that there is no need to avoid food allergens during pregnancy, which is in line with current international guidelines. It is important to note that these guidelines do not actively recommend intake of food allergens,” Venter added. “All pregnant women should ideally consume a healthy, varied diet if possible.”

As for why C-sections may make some children more susceptible to allergic disorders, it goes back to the interruption in the transmission of the maternal microbiome and subsequently compromised intestinal microbiome that happens when an infant doesn’t pass through the birth canal, Galowitz said.

“This all goes back to our more global idea of the ‘hygiene hypothesis,’ or that the lack of early introduction of germs represses proper immune system development in infants/children,” she said.

C-sections aren’t typically recommended unless a doctor suggests the procedure, so it’s advised to try for a vaginal delivery if there are no indications requiring C-section, Galowitz said.

Women should keep in mind that the study doesn’t say that having a C-section or giving an infant formula will cause allergy issues.

“There are many reasons — both voluntary and nonvoluntary — that women deliver via C-section or choose to use formula, and they shouldn’t feel shamed for whatever they choose,” Galowitz added.

If a child shows early signs of an allergic disorder, such as having eczema, the parents should seek help from an allergist. Doing so early in life may help minimize the severity of allergies, Galowitz said.