Issue 038

What can a birth chart tell you about your health?

Yvette Rose · 7 min read

A birth chart cannot diagnose you, predict an illness or stand in for a blood test, and when astrology has been tested under controlled conditions it has not beaten chance. I am a certified Hellenistic astrologer and I say that without hesitation. What a chart can do is give you a map of timing and a structured way to reflect on your own life. Used that way, alongside real medicine, it has a place in my practice.

What happens when astrology is tested

The best known test was published in the journal Nature in 1985. Each of 28 astrologers was given a birth chart and three personality profiles and asked to pick the profile that belonged to the chart's owner. They expected to be right more than half the time. Across 116 trials they chose correctly 34 percent of the time, which is what guessing gets you with three options.

Newer and larger studies agree. In 2024, a study of 12,791 US adults found that zodiac sign explained 0.3 percent or less of the differences in wellbeing between people. A random number from 1 to 12 predicted just as well. A study in China covering more than 173,000 people found that sun sign did not predict personality.

Those studies test sun signs and personality matching, and a full chart reading is a more detailed thing. Even so, I know of no controlled study showing that any chart technique can identify or predict disease. Anyone who tells you otherwise is selling certainty they do not have.

Why a reading can still feel exactly right

In 1949 the psychologist Bertram Forer gave 39 students what looked like individual personality reports. Every student received the same text, taken largely from a newsstand astrology book. They rated its accuracy at an average of 4.3 out of 5. General statements feel personal. That is true of horoscopes, and it is true of plenty of wellness advice.

Expectation is also physical. In drug studies, patients who were told about a possible side effect reported it far more often than patients who were not told. For one blood pressure medication the numbers were 31 percent versus 16 percent. Doctors call this the nocebo effect. It is the reason I will never tell anyone their chart "shows" an illness. Say that to a worried person and you may hand them the symptoms.

Where birth timing does show up in medicine

Here is the part that surprises people. When you were born does track with your health, and the reasons come down to seasons and school calendars. Researchers at Columbia examined the records of 1.7 million patients in New York and found 55 conditions linked to birth month. Their explanations were earthly ones: sunshine and vitamin D, winter infections during pregnancy, and dust mites in a baby's first months. The authors added that the pattern probably reflects New York's climate, so it would look different somewhere else.

ADHD is the clearest example. In US states where the school cutoff is September 1, children born in August are the youngest in their class and children born in September are the oldest. The August children were diagnosed with ADHD at a rate of about 85 per 10,000, compared with about 64 per 10,000 for the September children. A few weeks of birthday, a different seat in the classroom, a different chance of a diagnosis.

If you are a younger reader with a late summer birthday and an ADHD diagnosis, this is worth knowing and it does not mean your diagnosis is wrong. A 2023 analysis found that the youngest children in a class were no more likely to lose the diagnosis as they grew up.

A chart is a map of timing. Your bloodwork is the ground you are standing on.

How I use a chart in practice

Medicine and astrology shared a room for a long time. A medical book printed in 1493 shows the zodiac man, with each sign governing a region of the body, and practitioners used the position of the Moon to choose when to bleed or medicate a patient. Medical astrology was widely practiced in Europe from the fifteenth to the seventeenth century, and by the eighteenth century astrologers had largely been shut out of learned medicine. I read that history as history.

What I kept from the tradition is its sense of timing. Hellenistic astrology has a technique called annual profections. It starts from the rising sign at birth and moves one sign for each year of life, so every year hands the focus to a different part of the chart. The sixth place is the one the tradition ties to illness and injury, and by that count it comes up at ages 5, 17, 29, 41, 53 and 65. In those years I ask one question: how is your body being looked after right now? I make no predictions from it.

Used this way, a chart is structured reflection, and reflection has modest evidence behind it. Across 138 studies, people who monitored their progress toward a goal were more likely to reach it, and more so when they physically recorded it. Writing about difficult experiences shows a small average benefit across 146 studies. A chart gives some people a reason to sit down and do that work.

Plenty of people are curious. About 27 percent of US adults say they believe in astrology, and only one percent say they rely a lot on what they learn from it. That proportion sounds right to me.

What I would do first

I would treat a chart reading the way I treat a good journal prompt. Ask what it makes you notice: which years were hard, what keeps repeating, what you have been putting off. Write the answers down, with dates.

Then I would take those dates to the real record. Line them up with your labs, your sleep, your cycle if you have one, and your family history. If a reading says this is a year for the body, the action is a checkup, and the chart's job ends there.

Choose an astrologer the way you would choose any practitioner. One who says your chart shows thyroid disease, or tells you to stop a medication, has left their lane. In both of my professions I do not diagnose, order tests or treat, and I refer out when something needs a doctor.

When to push harder with your doctor

Any symptom that is new, getting worse or frightening goes to a doctor on the body's schedule. No transit, retrograde or "bad year" is a reason to wait, and no "good year" is a reason to skip a screening.

The cost of replacing treatment with belief has been measured. Among patients with curable cancers, those who chose alternative medicine alone had 2.5 times the risk of death of those who took standard treatment. That study looked at alternative medicine in general and did not study astrology. I include it because the principle carries: use the map and the medicine together.

If a reading has left you anxious about your health, tell your doctor in exactly those words. "Someone told me I am at risk and I cannot stop thinking about it" is a legitimate reason for a visit.

FAQ

Can astrology predict illness?

No. Controlled tests have found that astrologers match charts to people at the rate of chance, and large studies find no link between zodiac sign and personality or wellbeing. A chart is useful for reflection and timing, and it cannot tell you what is happening in your body.

What is medical astrology?

It is the old practice of linking signs and planets to parts of the body and timing treatment by the sky. It was widely practiced in Europe from the fifteenth to the seventeenth century, and physicians used the Moon's position to time bloodletting. It faded from learned medicine after that.

Does the month you were born affect your health?

In small ways, yes, through seasons and school calendars. One study of 1.7 million patients found 55 conditions linked to birth month, with explanations such as sunshine, vitamin D and winter infections. Children who are the youngest in their class are also diagnosed with ADHD more often.

Is it harmful to use astrology for health decisions?

Using a chart for reflection alongside regular medical care is low risk. The harm comes from delaying or refusing care, or from being told your chart shows a disease, since expectation alone can produce symptoms. Keep your screenings, your prescriptions and your doctor.

How does a health coach use a birth chart?

I use it as a timing map and a prompt for reflection. It helps me ask better questions about what a particular year is asking of someone, and the answers get checked against labs, history and how the person feels. I do not diagnose, order tests or treat, and I refer out when a doctor is needed.

In good health,
Yvette Rose

Sources

This is general wellness education and not medical advice, diagnosis or treatment. Talk to a qualified professional, especially if you are pregnant, nursing, taking medication or managing a condition.

It all starts in the gut.