What sounds at first like some kind of crazy “allergy astrology” or “health horoscope” is actually some cutting-edge research just out of the University of Southampton: There's a link between the season in which you are born and allergy risk later in life.

The Southampton study, published in the journal Allergy, conducted epigenetic scanning on DNA samples from a group of people born on the Isle of Wight. They found that particular epigenetic marks were associated with season of birth and still present 18 years later. The research team was also able to link these birth season epigenetic marks to allergic disease, for example people born in autumn had an increased risk of eczema compared to those born in spring. The results were validated in a cohort of Dutch children.

Epigenetics is the study of how cellular and phenotypic trait variations can caused by factors other than genetics, factors external to the DNA sequence.

John Holloway, Professor of Allergy and Respiratory Genetics at the University and one of the study’s authors, comments: “These are really interesting results. We know that season of birth has an effect on people throughout their lives. For example generally, people born in autumn and winter are at increased risk for allergic diseases such as asthma. However, until now, we did not know how the effects can be so long lasting.”

After measuring whole blood epigenome-wide DNA in 367 participants, the Southampton team found that DNA methylation was associated with birth season, and it was still present 18 years later. In addition, the researchers were able to link the birth season epigenetic marks to allergic diseases. Specifically, people born in autumn had an increased eczema risk, compared with those born in spring.

Previous studies have suggested that summer babies grow up to be healthier adults, pointing to maternal vitamin D exposure during pregnancy and its effect on offspring.

The team say that further research is needed to understand what it is about the different seasons of the year that leads to altered disease risk, and whether specific differences in the seasons including temperature, sunlight levels and diets play a part. More study is also needed on the relationship between DNA methylation and allergic disease, and whether other environmental exposures also alter the epigenome, with potential disease implications.