A new study has found that children born to mothers lacking a specific fatty acid in their blood during pregnancy face a significantly higher risk of developing asthma in early life, shedding fresh light on how prenatal conditions shape long-term respiratory health.

Childhood asthma—often marked by shortness of breath, persistent coughing, and frequent respiratory infections—remains one of the most widespread chronic illnesses among children globally. Increasingly, scientists are tracing its origins back to the earliest stages of life, including the prenatal period.

Researchers from the University of Copenhagen and the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), based at the Danish Pediatric Asthma Center, examined the role of a fatty acid molecule known as 12-HETE in pregnant women. Their findings suggest that the absence of this molecule is associated with a markedly higher likelihood of children developing asthmatic bronchitis within their first year.

Over a ten-year observation period, the study found that children whose mothers lacked measurable levels of 12-HETE faced a 62 percent higher incidence of asthma compared to those whose mothers had detectable levels. However, researchers caution that the findings establish correlation rather than direct causation.

The study also identified broader health implications. Infants born to mothers without measurable 12-HETE were more prone to repeated respiratory infections and showed distinct differences in airway bacterial composition. These early-life changes in the microbiome and immune response are believed to contribute to the elevated asthma risk.

According to the researchers, differences in airway biology can be detected as early as one month after birth. Lower levels of the fatty acid during fetal development may impair immune system maturation, leading to an altered lung microbiome and increased vulnerability to infections.

The findings also add nuance to the role of omega-3 supplements during pregnancy. While earlier research has suggested that omega-3 intake—commonly through fish oil—can help reduce asthma risk in children, this study indicates that the benefit may depend on the presence of 12-HETE. Among mothers with measurable levels of the fatty acid, omega-3 supplementation was linked to a 58 percent reduction in early childhood asthma. No such effect was observed in mothers lacking the molecule.

This suggests that blanket supplementation strategies may not be equally effective for all pregnant women, and future interventions could be tailored based on individual biological markers.

Despite the promising insights, researchers stress that the findings are not yet ready for clinical application. More precise benchmarks for measuring 12-HETE levels are needed before it can be used to guide treatment or prevention strategies.

The research draws on data from two major cohorts—the Danish COPSAC2010 study and the US-based VDAART cohort—tracking more than 1,600 mothers and their children. The consistency of findings across both groups strengthens the reliability of the results, even as questions around causality remain unresolved.

Taken together, the study points to the potential of 12-HETE as a biomarker that could one day enable more personalised approaches to preventing childhood asthma—an area of growing urgency given the condition’s global prevalence.