Horoscopes aside, your birth month really does affect your health

May 8, 2023

Providence Health Team

[5 MIN READ]

Although astrology is not based in science, researchers have found that certain health conditions could be related to the month in which you were born.
One study showed that people born in March may have a higher risk of heart disease.
Another study suggested that autumn babies could be more athletically gifted than children born during other seasons of the year.

Do you eagerly read your astrology chart every day to learn what’s in store for you? Or do you scoff at astrology and prefer to rely on scientific studies when making plans for your life? Either way, we have news that will interest you: Your birth month could have a significant impact on the diseases you develop during your lifetime, according to some studies. It has nothing to do with how the stars are aligned, and everything to do with the time of year you were born, and how the conditions at that time affected your future development.

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. One in 40 atrial fibrillation cases could relate to seasonal effects for a March birth.

The researchers theorized that the relationship between heart disease and birth month could be explained by the amount of vitamin D available to babies. During the winter, pregnant women receive less vitamin D, even when they take supplements. Therefore, a baby born in March would have received less vitamin D than one born in, say, September. Studies have indicated that decreased levels of vitamin D can lead to high blood pressure and high cholesterol — both of which are risk factors for cardiovascular disease.

In the study, which was published in the Journal of the American Medical Informatics Association (JAMIA), researchers checked to make sure the 55 diseases for which they found associations with birth months were not by chance. They also were careful to note that the relation to birth month is relatively minor in comparison to other variables like diet and exercise.

In what month were you born? You may be at risk for these diseases

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 syndrome: June-August
Eating disorder: February-May
Epilepsy: January-March
Glaucoma: April-June
Multiple sclerosis (Northern Hemisphere): April-June
Multiple sclerosis (Southern Hemisphere): October0December
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 stands out for finding connections between birth month and mental health. This 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 compared to 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 year or being born in a month with less sunlight could affect physical and mental functions, as is observed in seasonal affective disorder.

Seasonal effects

Other studies have found relationships between seasons and certain attributes. For example, an International Journal of Sports Medicine study found that autumn babies tend to be more successful at athletics than children born in other seasons of the year. Specifically, those who were born in November are “fitter and more powerful” than those born in other months of the year, particularly during the summer.

Does that mean that if you are born in July, you shouldn’t even try to participate in sports? Of course not! 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, preventive care from a skilled doctor is the best way to safeguard your health.

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