How Diseases Can Be Linked to Your Month of Birth Your birth month may have a significant impact on your risk of developing certain diseases throughout your lifetime. In a study of 1,688 different health conditions, 55 were significantly dependent on birth month.1 While 19 of these associations were previously reported in medical journals (such as asthma and short-sightedness), and 20 were for diseases with close associations to those already reported, 16 new connections were revealed – including nine different types of heart disease. Overall, those born in May had the lowest disease risk while those born in October had the highest, but there were many additional variables reported. According to the researchers:2 “Hippocrates described a connection between seasonality and disease nearly 2500 years ago, ‘for knowing the changes of the seasons… how each of them takes place, he [the clinician] will be able to know beforehand what sort of a year is going to ensue… for with the seasons the digestive organs of men undergo a change.’” Following in footsteps laid more than 2 millennia ago, recent studies have linked birth month with neurological, reproductive, endocrine and immune/inflammatory disorders, and overall lifespan.” What Does Your Month of Birth Say About Your Health? Several trends stood out to the researchers, including those linking neurological, reproductive, endocrine, and immune system health with birth month. Specifically, people born in: March and April were more likely to have heart issues, including atherosclerosis October and November were more likely to suffer from bronchitis, viral infections, and attention deficit hyperactivity disorder (ADHD) December were more prone to bruising September had a higher risk of vomiting January were more likely to suffer from essential hypertension Past research has also linked birth month with various diseases. In 1983, researchers found those born from May to September, when dust mites tend to be more abundant in the home, had a 40 percent increased risk of developing asthma, complicated by dust mite allergies.3 According to the featured study, “Their finding was corroborated later when it was found that sensitization to allergens during infancy increases lifetime risk of developing allergies.”4 Last year, researchers also found Swedish children born in November and December had an increased risk of being diagnosed with ADHD, which they suggested might be due to their relative immaturity age-wise relative to their peers in school.5 Researchers of the featured study found a similar trend:6 “We compared our ADHD smoothed proportions to odds ratios reported by a Swedish study and found a similar upward trend towards the later part of the year peaking in November. A rationale for their findings (and ours) is that relative immaturity (born later in the year) may result in increased ADHD detection. This occurs because more immature children (i.e., younger in age) face higher demands early on in their school years making them more susceptible to ADHD diagnosis. The age cutoff for schools in Sweden is 31 December, which is the same for NYC public schools.” Birth Month Influences Your Sun Exposure and Vitamin D Many of the associations could have their roots in sun exposure, which increases vitamin D levels. For instance, babies born in spring have a higher risk of heart issues later in life, and spring babies would have been in utero during the winter months, when sun exposure, and vitamin D levels, tend to fall. Vitamin D is very important for reducing hypertension, atherosclerotic heart disease, heart attack, and stroke, which brings the connection full circle. Further, that ADHD is more commonly diagnosed in children born in the fall and winter could also be related to vitamin D status. According to the featured study:7 “…the relationship between Vitamin D and ADHD and learning patterns has been established in rats and Vitamin D deficiency in early development (in utero or shortly after birth) could be related to ADHD.” In addition, past research found that those who were born in April or May, just after the darker, colder winter months, were significantly more likely to have multiple sclerosis (MS) than those born during October and November (after the summer months).8 Vitamin D may affect MS risk by altering chemicals called cytokines, which modulate your immune system and can either reduce or increase inflammation depending on their levels and proportions. Food Allergies and Mood Also Linked to Birth Month Similarly, US children (those living in Boston, in particular) born in fall and winter also have a higher risk of developing food allergies, which researchers again believe is due to seasonal fluctuations in sunlight and lower vitamin D levels.9 Even your mood might be affected by your birth month or, as researchers call it, your “seasonal biology.” Animal studies suggest mice raised in winter conditions (with less daily light exposure) may be prone to poor mood, including seasonal affective disorder, while mice raised in summer conditions had happier dispositions.10 Researcher Professor Douglas McMahon told the Daily Mail:11 “Several studies show that people born in the winter months have an elevated risk of mood disorders such as seasonal depression, bipolar depression and schizophrenia – all of which are associated with disruption of normal circadian rhythms… Whether seasonal birth could impact personality and mood is speculative, but not too far-fetched. Even though this sounds a bit like astrology, it is not: it’s seasonal biology.” Even Time of Conception May Matter… You probably rarely think about your health in relation to your birth month, let alone the month in which you were conceived, but even this may impact your future health. Specifically, birth defect rates tend to be highest for women who conceive in the spring and summer – a time that correlates with increased levels of pesticides in surface water.12 Researcher Paul Winchester, M.D., Indiana University School of Medicine professor of clinical pediatrics, noted:13 “Elevated concentrations of pesticides and other agrochemicals in surface water during April through July coincided with significantly higher risk of birth defects in live births conceived by women whose last menstrual period began in the same months. While our study didn't prove a cause and effect link, the fact that birth defects and pesticides in surface water peak during the same four months makes us suspect that the two are related.” Rerferences 1, 2, 4, 6, 7 Journal of American Medical Informatics Association June 3, 2015 3 Clin Allergy. 1983;13(6):529–535. 5 Journal of Child Psychology and Psychiatry Volume 55, Issue 8, pages 897–904, August 2014 8 Journal of Neurology, Neurosurgery and Psychiatry November 14, 2012 9 Ann Allergy Asthma Immunol. 2010 Apr; 104(4): 307–313. 10 Nat Neurosci. 2011 Jan;14(1):25-7. 11 Daily Mail December 6, 2010 12 Acta Paediatr. 2009 Apr;98(4):664-9. 13 Indiana University News Room 14 Newsweek June 10, 2015 Source
