A new study by Danish scientists has revealed an unexpected link between the composition of a pregnant woman's blood and the risk of her child developing asthma. It turns out that the absence of a specific fatty acid—the 12-HETE molecule—in the mother's blood significantly increases the likelihood that the child will face asthmatic bronchitis at an early age. The research was published in the journal Cell Reports Medicine.

The study was conducted by specialists from the University of Copenhagen and the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC). Researchers monitored hundreds of mothers and children over a ten-year period, analyzing maternal blood samples during pregnancy, the airway microbiomes of infants, and the frequency of respiratory diseases in the children.

The key focus of the study was the fatty acid 12-HETE, a biologically active molecule involved in immune processes. For children whose mothers lacked detectable levels of this molecule in their blood during pregnancy, the risk of developing asthma in the first ten years of life was 62% higher. Furthermore, these children suffered from respiratory infections more frequently and exhibited a markedly altered bacterial composition in their airways as early as one month of age.

The authors believe that 12-HETE may play a crucial role in shaping the fetal immune system while still in the womb. According to lead researcher Bo Chawes, a deficiency of this molecule likely disrupts the early maturation of immunity and affects the lung microbiome, increasing susceptibility to infections and asthma.

The scientists also examined the impact of Omega-3 supplements during pregnancy. While it was previously known that fish oil can reduce the risk of asthma in children, the new study revealed a vital detail: the protective effect was observed only in women who had 12-HETE present in their blood. In this group, the probability of early childhood asthma was 58% lower compared to the placebo group. Conversely, if the molecule was absent, Omega-3 supplements had virtually no effect.