Cord Blood Reveals Allergy Markers at Birth

New research has discovered that certain immune changes seen in cord blood are linked to later development of food allergies in babies. Will this lead to a cure?

Cord Blood Reveals Allergy Markers at Birth SvetlanaFedoseyeva/Shutterstock

Food allergies in kids are on the rise, yet the cause remains a mystery. Because the effects of these allergies can be so serious, many new moms are rightly concerned about what they can do to prevent them in their babies. Although we still have no cure for food allergies, a new study published in the journal Science Translational Medicine has found an immune marker present at birth—one clue that could help lead to better identification and maybe even prevention of allergies.

Some infants "primed" for allergies

Researchers looked at over 1,000 women who gave birth, and found that those babies who went on to develop food allergies had hyperactive immune systems when they were born. "We discovered that infants who developed allergies to milk, eggs, peanuts, wheat and other common foods by twelve months of age have an abnormal profile of immune cells in their cord blood at birth," Len Harrison, M.D., D.Sc., a professor at The Walter and Eliza Hall Institute of Medical Research in Australia, tells Fit Pregnancy.

The immune cells, which normally work to fight infections, "were increased in number and were more activated, releasing more inflammatory chemicals, in babies who developed food allergy," Dr. Harrison says. This led to a new pattern of immune activity that made the babies susceptible to allergic reactions later. "These findings show that changes in the immune system that 'prime' the baby for allergies are present early on, at least at birth," Dr. Harrison says.

So what is causing the immune changes in the babies' cord blood? "We didn't find any relationship to the mode of delivery—vaginal versus elective or non-elective Caesarian—but there was a correlation with the duration of labor," Dr. Harrison says. "However, duration of labor was not correlated with food allergy itself, emphasizing that other factors post-birth must be at play."

Another piece of the allergy puzzle

This immune hyperactivity present at birth could reveal a piece of the puzzle of what is causing the increase in food allergies among children. Today, five percent of U.S. children have food allergies, and the CDC estimates that from 1997 to 2011 food allergies in kids increased 50 percent. "While underlying genetic susceptibility to allergy may be a factor, the rising incidence of food allergy over the last few decades points to the environment as the major culprit," Dr. Harrison says.

The next stage of research is to try to figure out what environmental factors are impacting the rise of allergies. "We will concentrate our efforts on how lifestyle and environment impact on the mother to create a more pro-inflammatory state in the baby," he says. The bacteria mom passes to her newborn at birth is critical for the development of the baby's immune system, so whatever affects mom affects baby, too. "A range of factors—diet, nutrition, vitamins, exposure to infection, antibiotics—that modify inflammation in the body are under scrutiny. If we can understand what's driving inflammation in the baby, we could design lifestyle and environment modification strategies to lower the chances of babies from being born with an increased risk of developing food allergy," Dr. Harrison says.

According to Dr. Harrison, food allergies are actually part of a bigger trend of rising immune-related diseases, including eczema, asthma, type 1 diabetes, multiple sclerosis and inflammatory bowel disease. "Abnormal immune development during early life is likely to be relevant to each of these conditions," he says. Theories as to why allergies and other immune conditions are increasing abound. It could be the result of our modern diet, which likely has too much sugar and fat. Or, it could even be the result of living in a world that's too clean, which means we're not exposed to as much bacteria. And this may be key, because mom's collection of bacteria "will be an important link to her environmental exposures and how she sets up the baby's immune system," Dr. Harrison says.

What can we do right now?

Until we have a better understanding of the causes behind allergies, could doctors test cord blood to simply identify which babies are at greater risk for them? Dr. Harrison says it's possible, but might not be practical. "While babies who develop food allergy have this immune signature, not all babies with the signature have developed food allergy," he says. "This immune signature may be a necessary but not sufficient requirement for allergy. Other factors are required after birth as well." Even if testing was done, it wouldn't be able to tell which food allergies would develop, he says.

Although we might not be able to yet pinpoint which children will have food allergies or why, this study is an important step to figuring it out. For now, if you are pregnant or nursing, recent research suggests that you go ahead and eat those allergenic foods, because avoidance is unlikely to prevent allergies—and in fact, might actually make your child more likely to have them. When your child is ready for solids, current guidelines are to introduce all foods (unless there is a family history of allergy) one at a time as soon as baby starts.