How Diseases Can Be Linked to Your Month of Birth

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Story at-a-glance -

  • Your birth month may have a significant impact on your risk of developing certain diseases throughout your lifetime
  • Those born in May had the lowest disease risk while those born in October had the highest
  • People born in March and April were more likely to have heart issues, including atherosclerosis
  • People born in October and November were more likely to suffer from bronchitis, viral infections, and attention deficit hyperactivity disorder (ADHD)

By Dr. Mercola

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.”

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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.”

Your Habits and Lifestyle Matter More Than Your Birth Month

You can’t do anything to change your birth month, and you certainly shouldn’t worry if you were born in October, which had the highest rate of disease associations. Nor should you feel your health is guaranteed if you happened to be born in the “healthiest” month of May. Your lifestyle choices matter far more for your ongoing health than your birth month. As reported by Newsweek:14

“The scientists behind the research have noted that other variables, such as an unhealthy diet and lack of exercise, play a far greater role in susceptibility to disease and advised that prospective parents should not worry about rearranging their reproductive calendars.”

I've previously written about how your environment and lifestyle, particularly your diet, has a direct influence on your genetic expression. For example, research using identical twins have shown that diet trumps genes in terms of the level of health you achieve.

The science of epigenetics also challenges the conventional view of genetics, proving that the environment determines which traits a gene will express, and that your fate is in no way written in stone even if you have genetic predispositions or are born in a certain “unhealthy” month. As an example, take a look at cancer research. While a lot of research money is funneled into genetic research, virtually nothing is spent on determining the extent to which our food and environment triggers the disease.

As mentioned, your genes will express or suppress genetic data depending on the environment in which it finds itself, meaning the presence or absence of appropriate nutrients, toxins, and even your thoughts and feelings, which unleash hormones and other chemicals in your body. Research into the health of our ancient ancestors also suggests that cancer is indeed a manmade disease, in large part caused by environmental factors such as:

Pesticide- and other synthetic chemical exposures A predominance of sugars and grains which causes the body to burn sugar rather than fat as its primary fuel Wireless technologies, dirty electricity, and medical diagnostic radiation exposure
Pharmaceutical drugs Obesity, stress, and poor sleeping habits Lack of sunshine exposure and use of sunscreens

Were this to be officially acknowledged to be at the heart of our cancer epidemic, people would likely demand a complete overhaul of most industries that provide us with everything from food and clothes to personal care products, furnishings and more. No one really wants to take that bull by the horn, and our flawed system allows these industries to pad the pockets of politicians and regulators who make sure they're protected from invasive scrutiny. And, this isn’t only relevant to cancer. Many other chronic diseases, from heart disease and diabetes to obesity and even likely Alzheimer’s disease, stem from poor diet, toxic exposures, inactivity, and other lifestyle factors.

How to Take Control of Your Health

Ideally you're already leading a healthy lifestyle, eating right, exercising, maintaining healthy vitamin D levels and managing stress, but if you're not, it's never too late to start. Each tissue only uses about 10 percent to 20 percent of its gene complement, and you want to be sure that those genes are the most advantageous ones possible for your health. You can begin to "remind" your cells to express in a healthful way, long before you manifest a disease, by encouraging your genes to express positive, disease-fighting behaviors by leading a healthy lifestyle.

No matter what your birth month or current state of health, I suggest you take matter into your own hands, educate yourself about health, and do that which is within your own power—which is a lot, by the way. Keep in mind that diet is only part of the equation. You can also turn your genes on and off with your emotions, and exercise has a direct impact on DNA as well. For more details, check out my 11 basic guidelines for health and longevity below.

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