When we are born can have an impact on our lives in various ways. The month of birth has been linked to personality traits, health outcomes, and even future success. But how much does the month you are born actually matter?
Personality Traits
Some research has found associations between birth month and certain personality traits. One study looked at correlations between month of birth and the Big Five personality dimensions (openness, conscientiousness, extraversion, agreeableness, and neuroticism). It found those born in May and June scored higher in extraversion and neuroticism compared to the rest of the year. Other studies have linked spring/summer births with increased novelty seeking and winter/fall births with higher persistence. However, the effects tend to be small and inconclusive.
One reason birth month could potentially impact personality is due to relative age effects. In school systems with cutoff dates, children born later in the year may be nearly one year younger than their older classmates. Younger age and relative immaturity could shape personality development. However, more research is needed to confirm if and how birth month truly affects personality traits.
Physical Health
Some research indicates that the season of birth influences physical health later in life. One study found a relationship between birth month and longevity. People born in October-December had slightly longer lifespans on average compared to those born in April-June. The authors hypothesized this may be linked to seasonal fluctuations in maternal nutrition during fetal development.
Other studies have found correlations between birth month and food allergies, eyesight, response to vitamin D supplementation, and susceptibility to viral infections like the flu. There are a few possible explanations. Nutrition and sunlight exposure during pregnancy and early infancy could program the developing immune system. Birth month may also correlate with environmental exposures later in life. For example, people born in autumn hit peak flu season at a younger, more vulnerable age. Overall, more research is needed to understand if and how birth month biologically impacts long-term health.
Mental Health
Birth month has also been associated with some mental health conditions. Multiple studies have found spring and summer birth months to be linked with increased risk for schizophrenia and bipolar disorder. One theory behind this is that viral infections during pregnancy could affect brain development. Birth month patterns have also been observed for conditions like ADHD, depressive disorders, and eating disorders, although findings are mixed.
The underlying causes are still uncertain, but researchers hypothesize environmental exposures before or shortly after birth could impact brain development relevant to mental health. Other potential factors like family history, gestational nutrition, or relative age may also play a role. More research is needed to determine if birth month is a reliable risk factor for mental health problems.
Academic Achievement
Relative age appears to be a strong predictor of academic abilities. Multiple studies show children born later in the academic year tend to have slightly poorer test scores and grades compared to older classmates. One study found US students born in August scored 5-12 percentile points lower on standardized tests compared to students born in September of the prior year. The gap was more pronounced early in schooling and less significant in higher grades.
Younger relative age likely contributes to immaturity, poorer self-confidence, and more behavioral issues at school entry. As a result, relatively younger children may be at a slight developmental disadvantage in academic achievement, especially early on. However, the differences tend to diminish as children get older. Overall, relative age seems to be more influential than birth month alone.
Future Income
Birth month shows some interesting correlations with earning potential and future income. One study in the UK found that adults born in September and October earned on average nearly 10% more than August-born counterparts. The trend was more pronounced in higher-paying industries like finance.
Relative age and time of school entry may impact development of confidence, social skills, or motivation – factors that can influence career success. There is also speculation that teachers treat older students preferentially, contributing to differences in academic performance that ultimately affect income. However, more research is needed to determine the magnitude and mechanisms behind the relationship between birth month and earnings.
Sports Achievement
Birth month appears to be linked with athletic skill and participation. In many youth sports leagues, eligibility cutoff dates result in relative age differences between teammates and competitors. This seems to confer an advantage to relatively older athletes.
In one study looking at European youth hockey leagues, roughly 60% of players on elite teams were born in the first quarter of the year. Data from professional sports like baseball, soccer, and hockey also reveal overrepresentations of birth months shortly after the cutoff date for a given age class. The differences likely emerge from more mature size, fitness, cognitive abilities, and emotional maturity of the relatively older athletes.
However, the relative age effect seems to fade over time. Looking at achievement in adult professional athletes, birth month patterns are much more evenly distributed throughout the year. Overall, birth month effects on sports achievement are largely explained by relative age.
Risk of Disease
Birth month may also impact the risk of developing certain diseases. Below are some key findings about birth month effects:
- Multiple sclerosis – Increased risk associated with spring birth months
- Asthma – Higher rates in fall and winter birth months
- Juvenile rheumatoid arthritis – Spring birth months linked to higher risk
- Type 1 diabetes – Spring birth months correlated with greater risk
The causes are not fully understood, but could involve maternal exposures during pregnancy, infant exposures after birth, relative ages, or virus patterns. Overall, more research is needed to confirm links between birth month and disease risk.
Summary of Birth Month Disease Risk Findings
| Disease | Birth Months With Higher Risk |
|---|---|
| Multiple sclerosis | March-May |
| Asthma | September-December |
| Juvenile rheumatoid arthritis | April-June |
| Type 1 diabetes | March-May |
Lifespan
Does your birth month influence how long you will live? Some research suggests it may play a small role. One large population study found a significant pattern in lifespan related to birth month:
- People born in October-December lived about 1 year longer compared to those born in April-June
- The average lifespan was 79 years vs. 78 years between the groups
- Heart disease mortality was also lower among those born in the last quarter of the year
Other studies have found similar effects, with autumn-born individuals outliving summer-born counterparts by 3-6 months on average. The reasons are unclear, but could involve programming of the immune system based on exposures during gestation and early life. More research is needed to confirm if birth month patterns influence lifespan.
Mortality Risk
Related to lifespan, birth month seems to impact overall mortality risk as well. Multiple studies have observed seasonal trends in mortality related to birth month:
- Highest infant mortality among those born in winter months
- Greater risk of suicide later in life for spring and early summer births
- Higher cardiovascular mortality for those born in April-June
The patterns may reflect maternal nutrition status, viral exposures during vulnerable developmental windows, and relative age effects. However, more studies are needed to explain the links between birth month and mortality risk over the lifespan.
Personality Summary
In summary, here are some key points about the links between birth month and personality:
- May-June births associated with higher extraversion and neuroticism
- Spring/summer births linked to increased novelty seeking
- Fall/winter births correlated with higher persistence
- Young relative age may shape personality development
- Overall, birth month effects on personality are inconclusive and weak
Mental Health Summary
Here is a brief overview of the evidence related to birth month and mental health:
- Spring/summer births linked to increased schizophrenia and bipolar disorder risk
- Patterns observed between birth month and depression, ADHD, eating disorders
- Possible factors involve prenatal infections, nutrition, chemical exposures
- Relative age and family history may also contribute
- More research needed to confirm birth month as mental health risk factor
Academic Achievement Summary
In summary, here is what we know about the link between birth month and academic performance:
- Children born later in academic year have lower test scores and grades
- Average 5-12 percentile point gaps on standardized tests
- Younger age contributes to immaturity, confidence, and behavior issues
- Differences less significant in higher grades
- Overall, relative age seems more influential than birth month per se
Conclusion
In conclusion, birth month may have some modest effects on our lives, but the impacts tend to be quite small. Findings related to personality, health, mental health, and achievement have been mixed and inconclusive. Relative age compared to peers often explains more than birth month alone.
While patterns exist, individual health and development are complex. Many other factors like genetics, childhood environment, and lifestyle behaviors likely outweigh any implications from birth month. More research is needed, but evidence indicates season of birth is not destiny. Although interesting, knowing someone’s birth month provides limited insight into that individual. Our experiences and choices still shape us much more profoundly.