What your birth month says about you, according to the data
Lifestyle
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3:00 PM on Wednesday, June 3
By Trevor Mahoney for ThatsThem, Stacker
What your birth month says about you, according to the data
Your birthday may feel like a personal milestone, but it’s also a unique data point among one of the most interesting patterns in American health and demographics. Scientists, educators, and epidemiologists have spent decades poring over birth records and medical histories to understand what the month you appear in the world says about your future.
That’sThem has pulled the stats from CDC Birth Data, Columbia University Irving Medical Center, EBSCO, The Mother Baby Center, and Oxford Academic to cover what your birth month may say about you, whether it’s about your disease risk or sports performance.
January: A slow start to the year
January ranks sixth in birth frequency across the U.S., sitting right near the middle of the pack based on 2022 CDC birth data. When counting back nine months, the conception window falls within April, which isn’t considered to be a peak conception period.
January babies do have one notable developmental edge, though. In the U.S., where the school enrollment cutoff is typically Sept. 1, those born in January tend to be among the oldest in their kindergarten class.
Research on the Relative Age Effect by EBSCO showed that older children in a classroom cohort tend to outperform younger peers in standardized tests and show lower dropout rates in athletics. This is a meaningful built-in advantage for winter-born students.
February: The rarest month of all
February stands as the rarest month for birthdays in America. Data from The Mother Baby Center outlines that just under 271,000 babies were born in February of 2023, compared to more than 322,000 in August.
This likely comes down to simple arithmetic. Since February typically only has 28 days, it has fewer chances to register births than any other month. Additionally, being born on Feb. 29 carries only a 1 in 1,461 chance of occurring, giving less than 0.1% of the world’s population this distinction. This uniqueness alone makes being born in February something to carry with pride.
March: An average month with a heart health flag
March comes in eighth for national birth totals, firmly setting it within the trough period of the year, alongside February and April. There is also a notable health anomaly to consider.
In a landmark study conducted by the Columbia University Irving Medical Center, analyzing 1.7 million patient records, it was found that people born in March faced a higher risk of atrial fibrillation, congestive heart failure, and mitral valve disorder out of all the birth months studied. Scientists were quick to note, however, that birth month is only a minor variable compared to diet, exercise, and other preventative lifestyle factors.
April: Second-rarest, low-mood risk research
April is the second-rarest month to be born in the U.S., with roughly 279,000 births recorded in 2023, per The Mother Baby Center. This is around 43,000 fewer than the reigning champion, August.
April also has a lighter health footprint compared to some of the other months. Research published in the Personality and Individual Differences journal found that spring-born individuals showed among the lowest associations with cyclothymic and depressive temperament profiles. For April babies, the seasonal health picture generally looks favorable.
May: The healthiest month to be born
If you had to pick the single best birth month to be born to maximize long-term health outcomes, May is it. The Columbia University study also cross-referenced 1,688 diseases against the records of the 1.7 million hospital patients and found that people born in May had the lowest overall disease risk of any birth month.
It’s believed by researchers that favorable prenatal conditions, including maternal sunlight exposure and nutritional factors during a winter pregnancy, may play a role.
June: Shoulder season for summer's baby boom
June lands fifth in U.S. birth rankings. CDC birth data confirms that births climb steadily from late spring into summer, typically driven by a fall conception surge as couples spend more time indoors during cooler months.
EBSCO’s research outlines how June babies are typically some of the youngest in their classes. This population also often scores lower on standardized assessments and has a higher dropout rate in youth sports, but the gap typically closes by the mid-teen years.
July: The runner-up birth month
July is the second-most popular birth month in the U.S. Based on information from The Mother Baby Center, nearly 312,000 babies arrived in July 2023. July babies benefit from the same fall conception surge that drives peak summer births.
The research from Columbia University makes an important distinction, though. July babies typically have an elevated asthma risk, which is loosely tied to peak-risk months for sunlight exposure during the prenatal period.
August: The month with the most births overall
Those born in August have a unique honor: They are a part of the most populous birth month. By raw count, The Mother Baby Center reports that more than 322,000 babies were born in August 2023, driven by peak conceptions in November.
August-born babies face a similar problem to June babies in that they are the youngest in their class if starting school in September. The Nuffield Foundation, in addition to Columbia University, found that this can meaningfully impact academic confidence and social development during a child’s early years.
September: The birthday month of champions
September is where the birth data gets quite interesting. While ranking fourth overall for monthly birth totals based on CDC data, nine of the 10 most common individual birthdays in the U.S. actually fall in this month. The clustering is believed to have been driven by elevated conceptions around the Christmas and New Year holiday season.
September also carries major academic and athletic advantages. September children would be the oldest in their class, assuming a Sept. 1 enrollment cutoff date, giving them a slight edge. Per EBSCO research, these students also boast higher test scores, develop social confidence faster, and are more likely to advance in sports.
October: High disease risk, but high athletic potential
October has a striking duality not seen in any other month. On one hand, the Columbia University data points out that people in October carry the highest overall disease risk of any birth month, with an elevated incidence of conditions such as asthma or cardiovascular issues.
However, a 2014 study published in the International Journal of Sports Medicine via the National Library of Medicine also found that October babies scored higher in grip strength than other months. So, October babies may benefit from greater health vigilance later in life on average, but they also show some natural physical advantages in childhood.
November: Resilient and physically strong
November comes in ninth for birth frequency, per CDC data, but near the top in physical performance research. The International Journal of Sports Medicine study detailed that children born in November boasted better cardiorespiratory fitness and lower-body power than peers in other months.
However, the Columbia University research notes an offset, which is that November babies see a slightly elevated risk of ADHD association.
December: The holiday birthday paradox
Finally, December is the third-rarest birth month in the U.S., per CDC data. Births drop noticeably around Christmas and New Year’s, which is often attributed to medical scheduling preferences and reduced holiday staffing during the holiday period.
December babies also have to contend with the “holiday birthday paradox,” which could result in celebrations and gifts for holidays and their birthday being combined into one. This can result in reduced individual recognition.
What the birth numbers really say
Birth patterns across the country are anything but random. They reveal a lot about the biology, behavior, and culture at the time in the U.S., as well as nine months previously.
It’s worth noting, however, that while researchers have found meaningful statistical connections between birth month and outcomes for diseases, birth month itself is a minor variable in cause. This is more modest in comparison to key influential health factors to consider, including having a strong diet and stable exercise. What your birth month reveals is simply a starting point and not your predetermined destiny.
This story was produced by That’sThem and reviewed and distributed by Stacker.
