Allergy is the most common chronic condition to begin in early childhood, and rates continue to climb worldwide. Today, most diagnoses happen only after a child experiences a reaction—meaning the opportunity to prevent the condition may already be lost. Now, new research suggests that a surprising source—the placenta—could help identify a child’s allergy risk at birth.
In a study published in Clinical & Experimental Allergy, researchers explored whether gene activity in the placenta could predict which children would go on to develop allergies. The placenta, typically discarded after delivery, acts as a biological record of the baby’s environment in the womb—capturing signals that may influence immune development before birth.
The team analyzed placental samples from two groups of Australian mothers and followed their children through early childhood. They focused on genes regulated by glucocorticoids—stress-related hormones known to influence immune function. Using machine learning, they identified five key genes—AFF1, ARID5B, IER3, ATF4, and SLC19A2—that were most strongly associated with later allergy outcomes.
The best-performing model showed moderate accuracy, correctly distinguishing between children who would and would not develop allergies better than chance. However, its strongest performance came in identifying children who were unlikely to develop allergies, suggesting the test may be more useful for ruling out risk than confirming it.
Interestingly, adding factors like maternal asthma or the child’s sex did not improve the model’s performance. This suggests that the biological signals captured in the placenta itself may provide more meaningful insight than traditional risk factors alone.
The findings also highlight the complexity of allergy development. No single gene predicted outcomes on its own—instead, risk appeared to emerge from interactions between multiple genes working together during pregnancy.
While promising, the researchers emphasize that this approach is still in early stages and not ready for clinical use. The study grouped multiple allergic conditions—including food allergy, eczema, and rhinitis—into a single category, and larger studies will be needed to refine predictions for specific conditions.
Still, the implications are significant. A reliable test at birth could help identify which children need closer monitoring—or reassure families when risk is low. Over time, such tools could shift allergy care from reactive treatment to early prevention.
