Does Your Birth Month Put Your Brain at Risk?

Is March’s child full of woe? A growing body of evidence suggests that the season in which a baby is born may affect everything from eyesight and eating habits to the risk of developing both mental and physiological problems later in life. A recent study reveals that our season of birth makes persistent and lasting changes to brain structures that influence our health, personality and behavior.

The season of birth (SOB) effect has been recognized since as early as 460 BC with the musings of Hippocrates, and has continued to be documented by modern research. Unlike astrology, however, these studies use scientific methodology to investigate and further understand the relationship between SOB and physiological and psychological traits, disorders and diseases.

The latest SOB cohort study, involving over 3 million people born in Sweden, identified that babies born in spring had a significantly increased risk of developing cutaneous malignant melanoma. The researchers suggest that sun avoidance may be critical during the first few months of life in determining your ultraviolet radiation susceptibility. Similarly, for those living in northern hemispheres, seasonal differences in UV light exposure and associated maternal vitamin D levels are linked with spring babies’ higher risk of multiple sclerosis (MS).

When it comes to neurobehavioral disorders, statistically significant associations have been made between SOB and the prevalence of schizophrenia, bipolar disorder and panic disorder, as well as traits such as lifespan, suicidality and novelty and sensation seeking. While proposed causal factors are likely combinatorial in nature, including differences in temperature, light, nutrition, maternal hormones and egg quality, new evidence indicates that these environmental variables impact brain development, with structural changes to the brain persisting through to adulthood.

Although many structural differences, both broad and discrete, were identified in the brains of those born in different months, the strongest overall effect was observed in the auditory cortex of males born in spring and summer. Compared with those born in fall and winter, these individuals had a smaller left superior temporal gyrus. Interestingly, this is a consistently replicated neuroanatomical feature of schizophrenia, especially suicide prone schizophrenics and is also a more prominent feature in individuals with suicidal depression, as opposed to those with non-suicidal depression. Again this highlights the link between spring-early summer babies and their increased likelihood of having neurobehavioral problems in adulthood.

So is there an ideal month to give birth when the health and wellbeing of your future child is concerned? Perhaps. Although there are records of autumn and early winter babies being prone to asthma, babies born in late winter through spring and into early summer draw the shortest straw as, collectively, they are at higher risk of developing a larger number of health issues from eating and mental disorders to cancer, Parkinson’s disease and MS.

In defence of all spring and summer babies out there, there has been a loose association between being born in spring and summer and being more of a novelty-loving, adventurous thrill-seeking type and it should be noted that there have been few studies on the SOB effect and more positive aspects of psychology, such as humor or creativity.

Oddly enough “March’s child being full of woe” seems to be in stark contradiction with our perception of springtime being the season of new birth. Thankfully, with the majority of human births in the world occurring in autumn, we seem to be inadvertently using the SOB effect to our advantage.


Crump C, Sundquist K, Sieh W, Winkleby MA, & Sundquist J (2014). Season of birth and other perinatal risk factors for melanoma. International journal of epidemiology PMID: 24453238

Dobson R, Giovannoni G, & Ramagopalan S (2013). The month of birth effect in multiple sclerosis: systematic review, meta-analysis and effect of latitude. Journal of neurology, neurosurgery, and psychiatry, 84 (4), 427-32 PMID: 23152637

Pantazatos SP (2013). Prediction of individual season of birth using MRI. NeuroImage, 88C, 61-68 PMID: 24246490

Image via Conrado / Shutterstock.

  • Anonymous

    Month of birth or month of conception?

    • Interesting point! Determining and characterizing the causal factors that bring the season of birth effect to bear can be an exceptionally complex task, due to the large potential number of seasonably varying factors that may influence the manifestation of a certain trait.

      In the SOB literature both birth-related and conception-related global, hemispheric, and local seasonably varying causal factors have been associated with influencing the SOB effect. So to answer your question (I think) both pre- and post-birth causal factors are linked with SOB.

      On a related note, some published studies associated with researching problems at birth, aimed to control for differences in length of gestation by using the month/season of conception as opposed to month/season of birth.

  • herb wiggins

    We might have real concerns about how the astrologers will misuse & abuse such findings, even tho the months they use in their star charts are 2 months away from the actual ascendancies of the current astrological signs, due to precession of the north pole. I’m sure that such misuse of these papers would give Phil Plait and the a lot of grist for their skeptical positions. grin.
    Herb W.

    • Haha, tee hee, yes exactly Philip Plait eat your heart out!

      It is super simple to illogically twist the results from SOB effect research to someone’s advantage, especially astrologers, making wild claims that it is some magical stardust from an individuals time of birth has caused the SOB effect (oh here we go again….sigh).

      Science claims are used to support all kinds of profitable nonsense, however its just a shame that the recognition of the validity and importance of these studies have been impeded by being inappropriately linked to Mystic Meg and Co 🙂 … this is science not astrology!

  • Anonymous

    I said yesterday (and you deleted my comment) that you should be ashamed of posting these things with this tone. Do you realize how much anxiety these kind of pseudo-scientific news produce into common people reading your blog?
    Instead of deleting me, please reply.

    • The season of birth effect (especially with the damaging association to astrology) has been confused with pseudoscience in the past, even by scientists! So it is not unsurprising you confused these studies with pseudoscience either.

      If you were a farmer for example, and noticed that only 10% of your sheep born in spring were underweight and unhealthy BUT a whopping 60% of your lambs born in winter were underweight and unhealthy their is clearly a season of birth effect. It is not pseudoscience, just a clear observation that countless people have made, both in and out of the lab for 1000s of years. It is also worthy of note that there are published studies which have concluded that for some traits there is no observable season of birth effect.

      While being born at a certain time of year DOES NOT mean you WILL have a disease/condition, it is that your are MORE AT RISK and that statistically, more people have the condition that are born then as opposed to at another time. This tells us that there is some temporal factor that influences the development of a condition/disease.

      Large cohort studies and meta-analysis involving millions of individuals coupled with careful design of the research and associated controls make for very convincing and enlightening studies that could help in the both the understanding, development and future treatment of a myriad of conditions.

      Properly understood, these studies should cause as much anxiety as discovering that eating meat, or being of a certain ethnic group puts you at higher risk of colon cancer or high blood pressure. Very useful information with regards to any preventative measures that can be taken to make the risk lower and help prevent ill-health.

Carla Clark, PhD

Carla Clark, PhD, is BrainBlogger’s Psychology and Psychiatry Section Editor and a scientific consultant, writer and researcher in fields including psychology and neuropsychology, as well as biotechnology, molecular biology and biophysical chemistry. She is also our newly appointed Digital and Social Media Manager. Follow her on Facebook or Twitter @GeekReports

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