Researchers from the University of Alicante in Spain analysed the birth month of nearly 30,000 people in relation to 27 chronic diseases to see if their birth season had an effect on their long-term health.

They found many links between the tendency to certain diseases and birth month – but these were promptly dismissed by statisticians as being no more scientifically valid than astrology.

Researchers suggest effect derived from seasonal changes

The researchers had speculated that seasonal changes in the environment, such as the amount of ultraviolet rays, vitamin D levels and viruses (more common in winter) could affect foetal development, or more specifically, the foetus’ immune system and overall health as an adult.

Professor Jose Antonio Quesada, who led the study, remarked that birth month “may behave as an indicator of periods of early exposure to various factors, such as exposure to ultraviolet rays, vitamin D, temperature, seasonal exposure to viruses and allergies which may affect the development of the uterus and neonate in their first months of life.”

“The differentiation of patterns by sex found that there may be a different vulnerability in men and women to these early exposure factors,” he added.

Published in the journal Medicina Clinica, the study claimed that overall, babies born in sunny September were least likely to be diagnosed with a chronic disease.

Women born in July experienced a 40% increased risk of incontinence and were more than a quarter (27%) more likely to be diagnosed with high blood pressure. Their male counterparts were nearly three times more likely to suffer thyroid problems than those born in January.

Men born in June were 34% less likely to be depressed and 22% less likely to be diagnosed with lower back pain; women born in June had a 33% lower risk of migraines and a 35% less chance of encountering problems related to menopause.

Women with osteoporosis were more likely to have been born in April, May, September and October, while men born in March, June and December seemed to be more likely to suffer from cataracts.

Links no more valid than star sign reading

The results, while interesting, were not received nearly so well by statisticians. Said Dr Robert Cuffe, an ambassador for the Royal Statistical Society, “Astrology has never made for great science”.

“If you look at 12 months for each of 27 conditions and two genders (628 possible links), you’re guaranteed to see chance patterns that appear amazing,” he said.

“Many of the conditions identified here are different to the ones identified in a similar study two years ago, which you wouldn’t expect if these were real associations.”

The aforementioned previous study in question was carried out by Columbia University, New York, in 2015. It examined 55 diseases, including asthma, ADHD and reproductive issues, and found links between an individual’s likelihood of contracting these diseases and their season of birth. For instance, October babies were more likely to be afflicted with several respiratory illnesses, but were also less likely to develop several cardiovascular diseases.

Nevertheless, it was noted that besides birth month, other variables could affect one’s chances of getting a chronic disease, including diet, exercise and stress levels. MIMS

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