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By Daniella Gray
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Children born to mothers aged 35 and older may be less likely to develop certain allergic conditions in early childhood, a new study has found.
Researchers from Japan and the United States analyzed health data on nearly 35,000 children and found that kids of older mothers were less likely to be diagnosed with food allergies in infancy and less likely to experience wheezing, eczema and sensitivity to house dust mites by the age of four.
The findings add nuance to conversations around “advanced maternal age,” which is often framed primarily in terms of medical risk.
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The study drew on data from the Japan Environment and Children’s Study, a nationwide project that followed more than 100,000 pregnancies across Japan between 2011 and 2014.
Researchers focused on 34,942 children who were followed from birth through age four. Parents regularly completed questionnaires about their children’s health and a subset of children also underwent blood tests to measure allergy-related immune responses.
The results showed that the likelihood of certain allergic conditions decreased as maternal age increased.
At one year old, around 6.6 percent of children were diagnosed with a food allergy, but that percentage dropped among children of older mothers. Roughly 7.3 percent of children born to mothers aged 25–29 had a food allergy diagnosis, compared with 6.1 percent of those born to mothers aged 35 to 39, and just 4.3 percent of those whose mothers were 40 or older.
Similar trends appeared for wheezing, a common early symptom associated with asthma. Infants born to mothers aged 35 and over were less likely to experience wheezing by age one, while children of younger mothers, particularly those aged 20 to 24, were slightly more likely to do so.
By age four, the pattern held. Children of mothers aged 35 and older had lower odds of having ever wheezed, lower rates of food allergy diagnoses, and reduced sensitivity to house dust mites—a common environmental allergen linked to asthma and eczema.
When both parents were 35 or older at the time of birth, children also showed lower odds of wheezing and food allergies compared with children whose parents were younger.
The researchers explained that allergic diseases are shaped by a complex mix of genetics, environment and lifestyle. Factors such as family history of allergies, exposure to smoke or pets, daycare attendance, household income and parental education were all taken into account in the analysis.
The study’s authors suggested several possible explanations why children of older mothers fare better when it comes to allergies.
Older parents may have more financial stability, access to healthcare and health knowledge, which could influence everything from prenatal care to early childhood environments.
Differences in lifestyle, stress levels and health behaviors may also play a role. While genetic and epigenetic changes associated with parental age are often discussed in terms of risk, the researchers note that these mechanisms may also interact with environmental factors in ways that reduce susceptibility to certain allergic conditions.
Importantly, the authors cautioned that the findings do not mean older maternal age is “protective” in a universal sense, nor do they negate known risks associated with later pregnancies, such as higher rates of chromosomal abnormalities or pregnancy complications.
Instead, the results highlight that the relationship between parental age and child health is more complex than previously understood.
They also noted that this is an observational study, meaning it can identify associations but cannot prove cause and effect. Further research is needed to understand the biological and social mechanisms behind the findings and to determine whether similar patterns exist in other populations.
Newsweek reached out to the study author for comment via email.
Do you have a tip on a health story that Newsweek should be covering? Do you have a question about allergies? Let us know via health@newsweek.com.
Reference
Yamamoto-Hanada, K., Harama, D., Sato, M., Miyaji, Y., Sakamoto, K., Nishizato, M., Yang, L., Kumasaka, N., Mezawa, H., Iwamoto, S., Pak, K., Nishizawa, T., Nadeau, K. C., Fukami, M., & Ohya, Y. (2026). Parental age and childhood allergy risk. JAMA Network Open, 9(1). https://doi.org/10.1001/jamanetworkopen.2025.54694
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