How Birth Month Is Linked to Disease

Researchers have known that there is an association between certain birth months and locations, and trends in health. For example, babies born in the winter months are more likely to develop type 2 diabetes. Fall babies are more prone, statistically, to a greater overall risk of depression. Asthma risk is greatest for New York City-area babies born in July and October. But why do these trends exist? A new study, published in the Journal of the American Medical Information Association, analyzed health data on 10 million patients, living in three countries and five different climates, to try to figure out what seasonal or environmental factors may explain these links.

For this study, electronic health records from the U.S., South Korea and Taiwan were used. “All of our major findings linking birth seasonal patterns with variance in environmental exposures fit into known mechanistic pathways,” wrote the study’s first author, Mary Regina Boland, Ph.D., in the school of medicine at the University of Pennsylvania. “This is crucial because it demonstrates the utility of our method and further underscores the importance of environmental exposures during development and the impact they may have throughout life.”

For example, the researchers found that mothers who were exposed to lower levels of sunlight in the third trimester of pregnancy had babies who grew up with an increased risk of developing type 2 diabetes. So for someone in the Northeast of the U.S., this would correlate to a December through March birthday. Another example: A woman exposed during her first trimester to a lot of particulate in the air, during times when air pollution is higher, went on to have offspring more prone to atrial fibrillation.

“We’re using data to connect the dots,” wrote study co-author Dr. Nicholas Tatonetti, PhD, an assistant professor of biomedical informatics at Columbia University Medical Center. By clarifying the connections, the researchers hope that they may someday be able to prevent birth-month disease risk. One idea would be seasonally adjusted prenatal vitamins, for example.