When it comes to understanding, maintaining or recovering our health, it’s natural to take into consideration things like lifestyle habits, diet, exercise, family health history and as we’ve stated for many years, past traumas and emotional well-being. In addition to these important factors, science continues to show that one aspect of our lives holds great influence over our health and yet, we would never think to suspect that it does. It’s the season in which we were born.

A very large study of 500,000 people from the U.K. has found that certain biomarkers are “significantly associated” with season of birth to a very high degree. These include birth weight, rate of maturation or onset of puberty and even height in adulthood. Because of this, it’s been determined that season of birth affects childhood growth and development in important ways.

Results showed that children born in the summer (June-July-August) had higher birth weights, entered puberty or had first menstruation later and were consistently taller, especially as adults, than children born in winter months (November-December-January).

Although summer babies had heavier birth weights, this did not affect their overall body mass index (BMI) later in life. Much of these results were attributed to the in utero vitamin D the babies received from their mothers via sun exposure, particularly during the second trimester, when bones are being formed, lengthened and programmed for adult life. The influence of vitamin D on the fetus in these and other vital ways was so important that the study said its effect was “as powerful as any genetic determinant.” In fact, in utero vitamin D exposure proved to be far more influential to a baby’s development in adulthood than even its own sun exposure in the three months after birth.

Everything an expectant mother is exposed to affects her baby, whether it’s diet, pollution in the environment, sun exposure and even the length of the day. Many studies have been done regarding the “fetal origins of adult disease” hypothesis, how they’re related to the season of birth and their impact on health outcomes years later. Much research has been done connecting the season of birth to proclivities for immune disorderscardiovascular disease, Type 1 & 2 diabetes, lifespan, whether you’re a morning/evening person, or even right or left handed. For example, a greater percentage of those born during autumn and the beginning of winter tend to live longer than those born during spring and summer. Interestingly, the most dramatic contrast in the U.K. study between babies born in different seasons was that of educational attainment. While it needs further study, babies born in autumn, particularly September and early October, showed a much greater degree of pursuing advanced educational attainment beyond high school.

It’s important to remember that every person is an individual, and personal overall health is made up of a composite of many factors, including those mentioned above. Even so, whether you’re investigating the mystery of a current health challenge or just want to do your best to support your existing health as you age, looking into your season of birth as it relates to health just might provide some interesting answers and strategies.

For more health insights from Dr. Sadeghi, please visit beingclarity.com to sign up for the monthly newsletter or check out his annual health and well-being journal, MegaZEN here. For daily messages of encouragement and humor,  follow him on Instagram at @drhabibsadeghi.

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