Researchers followed 172 pregnant women in Poland to see how their diet affected their babies’ chances of developing allergies. Women who ate more omega-3 fatty acids (found in fish), antioxidants (found in fruits and vegetables), and probiotics (healthy bacteria in yogurt) had babies with stronger, more balanced immune systems. By age one, babies born to mothers with high omega-3 intake had about 58% lower allergy risk, while those with probiotic-rich diets had about 45% lower risk. The study suggests that what mothers eat during pregnancy may actually reprogram their baby’s immune system to be less prone to allergies.

The Quick Take

  • What they studied: Whether the foods pregnant women eat can change how their baby’s immune system develops and whether the baby will be more likely to develop allergies.
  • Who participated: 172 healthy pregnant women aged 20-38 years living in Warsaw, Poland, followed from early pregnancy through their baby’s first year of life.
  • Key finding: Babies born to mothers who ate high amounts of omega-3 fatty acids (more than 13.5 grams per day) were 58% less likely to show signs of allergies by age one. Babies whose mothers ate probiotics regularly were 45% less likely to develop allergies.
  • What it means for you: If you’re pregnant or planning to become pregnant, eating foods rich in omega-3s (like salmon and walnuts), colorful fruits and vegetables, and probiotic foods (like yogurt) may help protect your baby from developing allergies. However, this is one study and more research is needed before making major diet changes—talk to your doctor first.

The Research Details

This was a prospective cohort study, meaning researchers followed the same group of women forward in time from early pregnancy through one year after birth. The 172 pregnant women recorded everything they ate at three different points during pregnancy (at 12, 24, and 36 weeks) using detailed food diaries and questionnaires. Researchers then tested the newborns’ blood from the umbilical cord to measure immune system markers and examine how certain genes were activated or deactivated. The babies were followed for one year to see which ones developed signs of allergies.

The researchers measured several immune system components in the babies’ cord blood, including special proteins called cytokines that help control immune responses, and they looked at whether certain genes related to immune tolerance were turned on or off. They also tracked which babies showed allergic symptoms during their first year of life.

This approach is valuable because it captures what mothers eat during the critical period when the baby’s immune system is developing in the womb, and it measures actual immune system changes in newborns rather than just asking parents about allergies later.

The immune system develops before birth, and what the mother eats during pregnancy may influence how that developing immune system is programmed. By measuring immune markers in newborn cord blood, researchers can see immediate effects of maternal diet on immune development. This helps explain the biological mechanism—not just whether allergies happen, but how the mother’s diet actually changes the baby’s immune system at a cellular level.

This study has several strengths: it followed women throughout pregnancy rather than asking them to remember what they ate, it measured actual immune system changes in newborns using sophisticated laboratory tests, and it had a reasonable sample size. However, the study was conducted in one city in Poland, so results may not apply equally to all populations. The study didn’t randomly assign women to different diets (which would be difficult and unethical in pregnancy), so we can’t be completely certain diet caused the immune changes rather than other factors. Additionally, the study measured allergic susceptibility at one year, but some allergies develop later in childhood.

What the Results Show

Babies born to mothers with high omega-3 intake showed significantly better immune balance. These babies had higher levels of interferon-gamma (a protein that helps fight infections) and IL-10 (a protein that calms down immune responses), while having lower levels of IL-4 and IgE (markers associated with allergic reactions). This pattern suggests the immune system was programmed toward protection rather than allergic sensitivity.

The omega-3 effect was particularly strong: mothers who consumed more than 13.5 grams of omega-3 per day had babies with 58% lower odds of showing allergic susceptibility by age one. Probiotics showed a similar but slightly smaller protective effect, with 45% lower odds of allergies in babies whose mothers consumed probiotics regularly.

At the genetic level, higher maternal omega-3 intake was linked to changes in how the FOXP3 gene was regulated—a gene important for immune tolerance. Higher probiotic intake was linked to changes in how the IL-10 gene was regulated, which helps calm down immune responses. These changes suggest the mother’s diet was actually reprogramming how the baby’s immune genes worked.

By 12 months of age, about 21.5% of all babies showed signs of allergic susceptibility, but this rate was much lower in babies whose mothers had high omega-3 or probiotic intake during pregnancy.

The study found that mothers who avoided highly allergenic foods (though the paper doesn’t specify which ones) while eating more antioxidants from fruits and vegetables also had babies with better immune profiles. The combination of high omega-3s, probiotics, and antioxidants appeared to work together to create the most balanced immune response in newborns. Interestingly, the protective effects were measurable in cord blood immediately after birth, suggesting the immune programming happened during pregnancy rather than after birth.

This research supports previous studies suggesting that what pregnant women eat matters for their baby’s immune development. Earlier research hinted that omega-3 fatty acids and probiotics might be protective, but this study provides more detailed evidence of how they work at the genetic and immune system level. The findings align with the general principle that early-life immune programming influences later allergy risk, though most previous studies looked at what babies ate after birth rather than what mothers ate during pregnancy.

The study was conducted in one location (Warsaw, Poland) with mostly healthy women, so results may not apply to all populations or to women with health conditions. The researchers couldn’t randomly assign women to eat different diets, so while the associations are strong, we can’t be completely certain that diet caused the immune changes rather than other lifestyle factors. The study measured allergic susceptibility at one year old, but some allergies don’t develop until later in childhood, so the long-term protective effects are unknown. Additionally, the study didn’t measure whether the babies actually developed clinical allergies (like eczema or food allergies), only immune markers suggesting increased risk. Finally, the study didn’t account for all possible factors that influence immune development, such as stress, sleep, or environmental exposures.

The Bottom Line

If you are pregnant or planning pregnancy, consider increasing omega-3 rich foods (fatty fish like salmon, walnuts, flaxseeds) and probiotic foods (yogurt, kefir, fermented vegetables) as part of a balanced diet. Eat plenty of colorful fruits and vegetables for antioxidants. These dietary changes appear to have moderate evidence supporting immune benefits for your baby’s allergy risk. However, this is based on one study, so discuss dietary changes with your healthcare provider, especially if you have allergies yourself or a family history of allergies. These recommendations are most appropriate for healthy pregnant women without dietary restrictions.

Pregnant women and women planning pregnancy should pay attention to these findings, especially those with a family history of allergies or who have allergies themselves. Parents of young children may find this information helpful for understanding allergy development. Healthcare providers caring for pregnant women may use this to inform dietary counseling. People with existing severe allergies should not assume dietary changes will reverse their condition, but this information may be relevant for future pregnancies. This research is less relevant for non-pregnant adults, though the general benefits of omega-3s and probiotics are well-established for overall health.

The immune programming appears to happen during pregnancy, with measurable changes visible in newborn cord blood immediately after birth. The protective effects against allergic susceptibility were measurable by 12 months of age. However, some allergies develop later in childhood, so the full long-term benefits are unknown. If you make dietary changes during pregnancy, you wouldn’t expect to see obvious changes in your baby until after birth, and allergic symptoms (if they were going to develop) typically appear in the first few years of life.

Want to Apply This Research?

  • Track daily omega-3 intake (target: 13.5+ grams per day from sources like fish, walnuts, flaxseeds) and probiotic servings (aim for at least one serving daily of yogurt, kefir, or fermented foods). Log these in the nutrition tracker with weekly summaries to monitor consistency.
  • Set a specific goal such as ’eat fatty fish 2-3 times per week’ and ‘include one probiotic food daily’ during pregnancy. Use the app’s meal planning feature to build recipes incorporating these foods, and set reminders for probiotic-rich snacks. Track which foods you enjoy most to build sustainable habits.
  • Create a pregnancy nutrition dashboard showing omega-3 and probiotic intake trends across trimesters. Set milestone goals for each trimester (e.g., ’establish probiotic routine by week 12’). After birth, note any allergic symptoms in your baby and correlate with your pregnancy nutrition data to see if patterns emerge. Share this data with your healthcare provider at prenatal visits.

This research suggests an association between maternal diet and baby’s allergy risk, but it is not definitive proof that diet changes will prevent allergies in all cases. Individual results vary based on genetics, environment, and other factors. Pregnant women should not make significant dietary changes without consulting their healthcare provider, especially if they have allergies, dietary restrictions, or medical conditions. This information is for educational purposes and should not replace professional medical advice. If your baby shows signs of allergies or allergic reactions, consult with a pediatrician or allergist for proper diagnosis and treatment.