Your month of birth could affect your health, but only very slightly.

It has been suggested for some time that the month of the year you are born in may have an impact on the disease you develop later in life. Nearly 2500 years ago Hippocrates described a potential relationship between the seasons and a person’s health:

“For knowing the changes of the seasons, the risings and settings of the stars, how each of them takes place, he will be able to know beforehand what sort of a year is going to ensue. Having made these investigations, and knowing beforehand the seasons, such a one must be acquainted with each particular, and must succeed in the preservation of health, and be by no means unsuccessful in the practice of his art.”

On Airs, Waters, and Places by Hippocrates

Recently, further investigation by researchers has been able to identify defects in neurological health, reproductive health, immune health and other disorders based on the month a person is born. Why would birth month affect your risk for a given disease? Well for something like asthma, studies have shown an increased risk for developing the disease in months where house dust mite levels are greater. Now, a new study by a group from New York has now expanded on the research into birth month and disease risk and identified the months that contribute most to overall health.

The study looked at over 1.7 million people who had gone to the Columbia University Medical Centre for treatment between 1900 and 2000. They compared the relationship between the month these people were born and the likelihood that they had any of the almost 1700 diseases. They identified 55 diseases whose incidence was influenced by someone’s birth month. These diseases included lung infections that peaked during October, bronchitis that peaked during November, asthma incidence in September, and heart disease in March. The researchers also saw that people born in May had the lowest disease risk and those born in October had the highest overall disease risk.

Should you be panicking? You cannot control the month you were born in so are we doomed from the get go? Are people born in May immune to certain diseases? Should people born in October live in a bubble? The answer is no. Although the associations found in this study are significant, they contribute only a very small increase in risk compared to other factors. For example, people born in November in New York were more at risk for developing ADHD. How much greater was this risk? About 1 in every 675 cases of ADHD may be attributable to the month you were born in. Take into consideration the number of people born in the month of November in New York who don’t have ADHD and you begin to see that there is much more at play than just the month you are born in. For something like heart disease, your diet and exercise regime is a much greater risk factor for disease then the month in which you are born. For asthma, exposure to viruses, allergens and your genetics is a greater risk factor than being born in September. It is also important to know that this data set only takes people from one place so the data is only translatable to people from New York or New York climate.

So what do we make of these results? Many of the increased risks were found in months that traditionally have less sunlight (September to March). Sunlight is important in helping your body produce vitamin D and vitamin D is important in preventing many diseases including, heart disease, asthma, and hypertension.

Again, don’t let these results scare you. The increased risk for these diseases is minute. The results from this study however are an interesting narrative on how your environment can impact your health.

Photo credit: Wikimedia Commons


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