Are babies born in May less likely to get ill than babies born in October? That's the astonishing assertion of a new study by Amercian scientists at Columbia University. The researchers are claiming that there really is evidence of a link between the month you're born in and your risk of developing certain diseases.


According to the study, which was published in the Journal of American Medical Informatics Association, things look a lot healthier for those born in May who had the lowest disease risk of any month. However, things aren't so rosy for October babies, who had the highest risk of disease.

"This data could help scientists uncover new disease risk factors," says study senior author Nicholas Tatonetti, PhD, an assistant professor of biomedical informatics at Columbia University Medical Center.

The surprising part of the study is that having tested over 1,600 illnesses, researchers may have found a link between birth month and 55 diseases including 9 types of heart diseases, as shown by the infographic below.



The research was based on the health records of 1.7 million New Yorkers who have been treated for ill health at the New York Presbyterian Hospital/Columbia University Medical Center - so the study only looked at those with medical issues.

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Also, it only represents one region in the US, and may not be representative of other areas or countries. The researchers stated that the health differences are most likely due to the climate and so suggest that the results are most comparable to northern European climates such as ours in the UK.

The lucky and not-so-lucky months - what you're more likely to suffer from in New York

  • January - Hypertension and cardiomyopathy (heart muscle disease)
  • February - Lung and bronchial cancer
  • March - Cardiac failure, mitral valve disorder and arrhythmia
  • April - Angina
  • May - A lucky month perhaps?
  • June - Severe angina
  • July - Asthma
  • August - Another illness free month
  • September - Vomiting
  • October - Insect bites, chest infections and asthma
  • November - ADHD
  • December - Bruising

This isn't the first piece of research that has tried to find a connection between what time of year you are born and your health. Studies in Sweden echoed the New York research that suggested a higher risk of ADHD in children born in November.

In Denmark, children born in May and August were the most likely to suffer from asthma and breathing-related issues. Not the same months but digging a little deeper, the scientists found a connection - these months all have the same levels of sunlight.

Weather vs arrival date and size

In a different piece of research, Ben-Gurion University of the Negev (BGU) and Harvard University researchers discovered a link between weather and prematurity.

They observed that if it is hotter towards the end of your pregnancy, your baby might arrive sooner than expected and be a smaller baby.

"We found that exposure to high air temperature during pregnancy increases the risk of lower birth weight and can cause preterm birth," explains researcher Dr Itai Kloog. "An increase of 8.5°C in the last trimester of average exposure was associated with a 17g decrease in birth weight of babies born full term after adjusting for other potential risk factors."

So should you plan to have babies in certain months then?

No, there's no need to take drastic action to try to influence your baby being born in one of the lower risk months. Nor should you feel concerned if your baby is born in a 'not-so-healthy' month. The most important factors when it comes to chronic diseases in later life are diet and exercise.

"It's important not to get overly nervous about these results because even though we found significant associations, the overall disease risk is not that great," says Dr. Tatonetti.

"The risk related to birth month is relatively minor when compared to more influential variables like diet and exercise."


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