Season of Birth Gives Clues to Health
Our Beloved Family:
In his book entitled, On Airs, Waters and Places, the ancient Greek physician, Hippocrates, stated, “Whoever wishes to pursue the science of medicine in a direct manner must first investigate the seasons of the year and what occurs in them.” What are the seasons, but the stages of progression of the natural world throughout the yearly cycle. Since nature is a closed loop and humans are part of that natural system, science is showing how deeply we’re connected to and affected by its laws, especially when it comes to our health and the season in which we’re born.
Although scientists are still trying to determine the exact cause(s), there are many large-scale research studies that show the time of year or season in which we’re born has a verifiable effect on things such as birth weight, onset of puberty, height in adulthood, and even overall lifespan. All studies referenced here break the year up into the traditional three-month seasons: spring (March, April, May), summer (June, July, August), fall or autumn (September, October, November) and winter, (December, January, February).
A UK Biobank Study consistently showed to a fairly high degree, that babies born in the summer have a higher birth weight, later start to puberty and grow taller as adults than those born throughout the rest of the year.
Research results across a wide range of large samples, most recently of 450,000 participants from the UK Biobank Study, consistently shows, to a fairly high degree, that babies born in the summer have a higher birth weight, later start to puberty and grow taller as adults than those born throughout the rest of the year. In contrast, babies born in winter weigh the least, enter puberty sooner and tend to be the shortest as adults. Those born in spring and fall are intermediate in these categories, with spring babies weighing more than autumn babies and growing taller as adults on average. Although the British study found no correlation between season of birth and body mass index (BMI), a Chinese study of 500,000 people has claimed a link between obesity in adulthood and those born in the spring and summer.
In utero vitamin D levels via a mothers’ exposure to sunshine, causes vitamin D levels in babies born in the summer to be nearly twice as high as those born in winter.
These findings are giving credence to what’s been called the “fetal programming hypothesis” or the theory that much of a child’s growth and development after birth are largely determined by influences while still in the womb and that these elements are independent of environmental and even genetic factors. While some have suggested things such as changes in available foods, air quality and physical activity as the year passes as possible causes, scientists have determined that a clear marker of these wide differences in babies based on season of birth is their in utero vitamin D levels via their mothers’ exposure to sunshine, especially during the second trimester. In fact, vitamin D levels in babies born in the summer are nearly twice as high as those born in winter.
Since the bulk of our vitamin D comes from sun exposure, it easy to see why the mothers of summer babies can get the best levels and pass that benefit on to their babies. Vitamin D isn’t as much of a traditional vitamin as it is a hormone precursor. Even its molecular structure is very similar to other hormones. That’s because vitamin D is crucial for cholesterol synthesis, and it’s from cholesterol that all of our other hormones are made, from pregnenolone, cortisol, and melatonin to progesterone, estrogen, testosterone, and all the rest. There isn’t a function in the body that’s not triggered by a hormone, and every one of those processes is dependent on vitamin D, which is at the top of the hormonal cascade.
“A scan of 1.7 million health records from the U.S. found that there were “robust” connections between many diseases in adulthood and season of birth.”
Because vitamin D is central to bone growth, it’s makes sense why summer babies with the highest amount from their mothers grow bones that are longer and stronger and end up taller as adults. Perhaps it’s the hormonal boost of vitamin D, compliments of mom, that helps them weigh more, as well. Although babies born in the fall and winter tend not to be as tall as adults, they do mature faster. This may be caused by an additional hormonal signal that triggers something in our primal biology that recognizes a baby born in the dark part of the year, when food and bounty are scarce, needs to grow up quicker as opposed to in the leisurely, bountiful summer. While researchers continue to search for clues, the differences between humans and season of birth, particularly with regard to physical and mental health later in life continue to surprise and perplex science.
By far, babies born in autumn are most likely to grow up and pursue higher education and advanced degrees. Researchers stated this educational data showed an “abrupt difference” even when comparing births from August, the last summer month just prior to the school year, to September. A scan of 1.7 million health records from the U.S. found that there were “robust” connections between many diseases in adulthood and season of birth. The strongest connections came with multiple sclerosis, which disproportionately affected those born in the spring and summer to a great degree, while celiac disease was experienced much more by patients born in the summer. In all, the research found 55 diseases that were strongly correlated with season of birth, including Type 1 diabetes, cardiovascular disease and mental health disorders. Schizophrenia, major depression and bipolar disorder were largely associated with those born in the winter and early spring, while suicide has shown to be a higher risk for those born in spring/summer versus fall/winter.
Understanding the seasonal risk factors that go along with various illnesses has helped me create powerful interventions for my patients, especially those dealing with mental health challenges, self-harm issues, and other such tendencies.
I strongly believe that a patient’s past informs his present and future health. When I say past, I mean going all the way back to what happens during gestation, emotionally and physically with the mother. A person’s present physical constitution, or what I call his physical terrain, is the result of everything he’s experienced physically, mentally and spiritually up to the current moment, much of which he may not be aware or even remember. Understanding the backstory of a patient’s current physical terrain is crucial in his accurate diagnosis and creating an effective plan of care. Of course, the information a patient’s season of birth can provide goes a long way toward that end. Understanding the seasonal risk factors that go along with various illnesses has helped me create powerful interventions for my patients, especially those dealing with mental health challenges, self-harm issues, and other such tendencies.
Overall, research shows that those born in autumn and the beginning of winter tend to have the longest lifespans, while those born in the summer have the shortest. Of course, no one is suggesting that season of birth alone predisposes a person to one type of condition or circumstance over others, but the evidence is clear that it plays a key role on some level. Researchers believe that one of the answers is vitamin D exposure for pregnant mothers. While many of the cases in these large research samples existed before prenatal vitamin D supplementation was recommended, perhaps it’s time to have your levels checked and discuss it with your doctor, especially if you’re pregnant, and considering the fact that vitamin D is crucial to a baby’s central nervous system development. It’s a simple test. Give us a call. We’d love to help you.
Love, Light, & Clarity in the Month Ahead,
Dr. Habib Sadeghi
Learn about a great way to be cold-free this winter.