Researchers studied whether the foods pregnant women eat can influence whether their children develop asthma. They created a special diet score based on foods that might protect against or increase asthma risk, including vegetables and yogurt (protective) versus fried foods and red meat (potentially risky). They tested this diet score in two groups of families—one in the USA and one in Sweden—to see if the same pattern held true in different populations. While the diet score worked well in the original US study, it didn’t predict asthma as clearly in the Swedish families, suggesting that diet’s effect on asthma may depend on other factors like where families live.

The Quick Take

  • What they studied: Whether a pregnant mother’s diet—specifically eating more vegetables and yogurt versus fried foods and red meat—affects her child’s chances of developing asthma.
  • Who participated: Nearly 4,700 mother-child pairs from two different countries: the USA (Healthy Start study) and Sweden (NorthPop study). The groups had different eating habits and backgrounds.
  • Key finding: In the US group, mothers with healthier diets (higher diet scores) had children with significantly lower asthma risk—about 59% lower. However, this same pattern didn’t hold true in the Swedish group, suggesting the diet-asthma connection may work differently depending on where families live.
  • What it means for you: Eating a diet rich in vegetables and yogurt during pregnancy may help reduce your child’s asthma risk, but this benefit might vary based on your location and other lifestyle factors. This is promising but not a guarantee, and more research is needed to understand why the effect differs between populations.

The Research Details

Researchers created a special ‘diet score’ based on seven food categories that previous studies linked to asthma and allergies in children. The score gave points for eating vegetables and yogurt (foods that seemed protective) and subtracted points for eating fried potatoes, cold cereals, juice, red meat, and rice (foods linked to higher asthma risk). They then followed two large groups of families from pregnancy through childhood, tracking what mothers ate during pregnancy and whether their children developed asthma diagnosed by doctors.

The first group (Healthy Start) was from the USA with about 945 mother-child pairs, and the second group (NorthPop) was from Sweden with about 3,710 pairs. The researchers used a statistical method called ’time-to-event analysis’ to see if mothers with higher diet scores (healthier eating) had children who were less likely to develop asthma over time.

This approach is valuable because it tests whether a finding from one population (the USA) actually works the same way in a completely different population (Sweden) with different food cultures and lifestyles. This type of ‘validation study’ helps scientists understand if research findings are truly universal or if they only apply to specific groups.

Understanding what pregnant women should eat to protect their children’s health is important because asthma affects millions of children and can be serious. If diet during pregnancy truly influences asthma risk, it’s a simple, safe way parents might reduce their child’s chances of developing this condition. However, researchers need to test findings in different populations to make sure the advice works everywhere, not just in one specific group.

This study has several strengths: it involved a large number of families (nearly 4,700), used doctor-diagnosed asthma cases (not just parent reports), and tested findings in two different countries. However, the fact that the diet score worked differently in the two populations raises important questions about whether the findings are truly reliable across all groups. The researchers were honest about this limitation, which is a sign of good scientific practice. The study relied on mothers remembering what they ate during pregnancy, which can sometimes be inaccurate.

What the Results Show

In the US Healthy Start group, the results were striking: mothers with higher diet scores (eating more vegetables and yogurt, fewer fried foods) had children with significantly lower asthma risk. Specifically, children whose mothers had the healthiest diets were about 59% less likely to develop asthma compared to children whose mothers had less healthy diets. This difference was statistically significant, meaning it was very unlikely to have happened by chance.

However, when researchers tested the same diet score in the Swedish NorthPop group, the results were very different. The diet score did not predict asthma risk in the same way. This was surprising and suggests that the protective effect of a healthy maternal diet may not work the same in all populations.

The two groups also had notably different eating patterns overall. Swedish mothers had higher average diet scores than US mothers, meaning they generally ate more of the ‘protective’ foods like vegetables and yogurt. Despite this healthier overall diet in Sweden, the specific diet score didn’t predict which children would develop asthma.

The study revealed important differences between the two populations. Swedish families had different dietary patterns and demographic characteristics compared to US families. These differences in lifestyle, food availability, and possibly genetics may explain why the diet score worked differently in each country. The researchers noted that other factors beyond diet—such as environmental exposures, healthcare access, or genetic differences—might play important roles in asthma development that weren’t captured by the diet score alone.

Previous research had suggested that certain foods during pregnancy might influence a child’s asthma risk, which is why researchers created the diet score in the first place. This study confirms that the diet-asthma connection exists in some populations (like the US group) but also shows that this relationship is more complex than initially thought. The findings suggest that diet alone may not be the whole story, and that other factors specific to different populations matter significantly.

The main limitation is that the diet score worked well in one population but not the other, which raises questions about how useful it really is. The researchers relied on mothers’ memories of what they ate during pregnancy, which can be inaccurate. The study couldn’t prove that diet directly causes changes in asthma risk—only that they’re associated. Additionally, the two populations were quite different in their backgrounds and lifestyles, making direct comparisons difficult. The researchers couldn’t account for all possible factors that might influence asthma risk, such as air pollution, pet exposure, or family history of allergies.

The Bottom Line

Based on this research, eating a diet rich in vegetables and yogurt during pregnancy appears to be beneficial and may help reduce asthma risk in children (moderate confidence level). However, the findings don’t apply equally to all populations, so individual results may vary. General healthy eating during pregnancy—including plenty of vegetables, fruits, and yogurt—is recommended for many reasons beyond asthma prevention. This research should not replace medical advice from your doctor about managing asthma or pregnancy nutrition.

Pregnant women and those planning pregnancy should be interested in this research, especially if they have a family history of asthma or allergies. Parents of children with asthma might find this information relevant for understanding risk factors. Healthcare providers working with pregnant patients may want to discuss healthy eating patterns. However, this research is not yet strong enough to make specific dietary recommendations for asthma prevention alone.

If maternal diet does influence asthma development, the effect would likely appear during early childhood, typically within the first few years of life. Asthma can develop at any age, but most childhood asthma cases appear before age 5. You wouldn’t see immediate results from dietary changes during pregnancy, but rather a potential reduction in asthma risk over the child’s early years.

Want to Apply This Research?

  • Track daily vegetable and yogurt servings during pregnancy, aiming for at least 3-4 servings of vegetables and 1-2 servings of yogurt daily. Also monitor and limit fried foods, processed meats, and sugary drinks to fewer than 2-3 times per week.
  • Use the app to log meals during pregnancy, with specific focus on adding one extra vegetable serving per day and replacing one sugary drink with water or plain yogurt. Set reminders for healthy snack options like yogurt or vegetable-based meals.
  • Create a weekly nutrition scorecard tracking the seven food categories from the diet index. Monitor trends over weeks and months of pregnancy. After birth, note any asthma symptoms in the child and correlate with maternal diet patterns during pregnancy to identify personal patterns.

This research suggests an association between maternal diet and childhood asthma risk but does not prove that diet directly causes asthma or prevents it. Results varied significantly between populations, indicating the findings may not apply universally. This information should not replace personalized medical advice from your healthcare provider. If you are pregnant or planning pregnancy, discuss your diet and asthma risk factors with your doctor. If your child has asthma or asthma symptoms, consult with a pediatrician or allergist for proper diagnosis and treatment. Dietary changes should be made in consultation with a healthcare provider to ensure adequate nutrition during pregnancy.