For centuries, physicians used astrology as a medical tool that helped diagnose certain conditions, illnesses and diseases. They believed signs of the zodiac had influence over specific body parts, and astrologers believed—without evidence—that the moon caused insanity. The medical profession has advanced significantly since then (to say the least) and no longer relies on star charts for diagnosis. However, there may be some seeds of truth behind the idea that the season of your birth month could affect your health.
The connection between birth month and disease
Depending on when you were born (winter, spring, summer or fall), you could have a higher or lower risk for: schizophrenia, multiple sclerosis, sleep disorders, Type 1 diabetes, heart disease, bipolar disorder, and allergies, to name a few. For example, experiencing seasonal dust mites in infancy connects to a significantly increased risk of developing asthma later in life. Dust mite allergen levels are usually highest between July and October; therefore people born during these months have historically higher rates of asthma and allergies.
Moreover, data scientists at Columbia University have discovered a relationship between birth month and nine types of heart disease. Their research shows that New Yorkers born in March face the highest risk of atrial fibrillation, congestive heart failure, and mitral valve disorder.
What your birth month says about your health
The reasons your birth month correlates to your health have to do with the complex ways in which human biology is modulated by seasonal changes. A study in Current Biology summarizes the conditions that have been reliably associated with birth month:
- Alcohol abuse: March – July
- Alzheimer’s disease: January – March
- Autism: March – August
- Bipolar disorder: January – April
- Type 1 (childhood) diabetes: March – June
- Down’s syndrome: June – August
- Eating disorder: February – May
- Epilepsy: January – March
- Glaucoma: April – June
- Multiple sclerosis (Northern Hemisphere): April – June
- Multiple sclerosis (Southern Hemisphere): October – December
- Narcolepsy: February – April
- Parkinson’s Disease: April – June
- Personality disorder: March – May
- Seasonal affective disorder: March – April
- Schizophrenia (Northern Hemisphere): December – January
- Schizophrenia (Southern Hemisphere): June – September
Among the studies of the correlation between various diseases/disorders and seasons of birth, a large meta-study conducted in 2003 stands out for finding connections between birth month and mental health. This meta-study analyzed more than 86 million births from 27 different parts of the world and concluded that people born in the winter months have an increased risk for schizophrenia than those born in months with more daylight hours.
All of this has to do with circadian rhythm, the internal clock that is central to many life functions. The body’s processes that influence everything from cell growth and reproduction to the functioning of digestive tissue, lungs, heart, liver, and patterns of social behavior depend in part on light — specifically, sunlight. Thus, changes in sunlight exposure over the course of the year or being born in a month with less sunlight could affect physical and mental functions, as is observed in seasonal affective disorder.
However, it is important to not be overwhelmed by these connections. Being born in a certain month does not mean that you are going to get a certain disease. Though associations between birth month and disease have been found, they are not fully understood, and the overall risk is part of a complicated mix of other variables like family history and lifestyle. It is also important to get your health information from trusted experts and not from pseudo-sciences like astrology.
Personalized, preventative care from a skilled doctor is the best way to safeguard your health. Find the Providence St. Joseph Health doctor that is right for you using our online provider directory.
This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.