If today’s your birthday — congrats! And, you’re not alone.
June 27 is the most popular birthday in Massachusetts, according to data from the state’s Department of Public Health.
Between 2005 and 2014, an average of 232.2 people were born on June 27 each year, the figures show.
The data detailed the birthdays of more than 750,000 people over that 10-year span.
The next most popular date of birth was Sept. 19, and it was a close second, with an annual average of 231.8 people born on that date during those years.
February 29, or Leap Day, was – by far – the least popular. For obvious reasons. It only came around twice during the 10-year period.
Advertisement
An annual average of just 37.9 people were born on that date, some in 2008 and the rest in 2012.
The next most uncommon date was a birthday that billions of people around the world celebrate.
A yearly average of only 130.8 people were born on Dec. 25, which Christians honor annually as the birth of Jesus.
The next least common birthday was Jan. 1, or New Year’s Day, with 140.8 people per year, on average.
Other uncommon birthdays also seem to fall around holidays, including Christmas, Thanksgiving, New Year’s Day, and the Fourth of July.
The data also shows that weekend births were significantly less common than weekday ones. The most common day to be born was a Friday, which averaged 230.1 births per day; the least common was a Sunday, which averaged 148.2 births per day.
Micaela Martinez-Bakker, a postdoctoral fellow at Princeton University, said the most likely reason why births occur much less often on weekends and holidays is because, in modern society, many deliveries are scheduled, either via induced labor or cesarean section procedures.
Martinez-Bakker co-authored a study showing how births tend to surge during certain seasons. She found that when those peaks occur varies based on how far people live from the equator.
Advertisement
The research, which focused on data from the US and other countries in the Northern Hemisphere, found that areas farther north of the equator tend to see births peak in early to mid-summer, while southern areas see their annual jump in births in late summer or autumn. Southern areas also see a more dramatic spike each year.
But researchers have not yet figured out what exactly causes seasonal variations in birth rates, Martinez-Bakker said.
“It’s still an open question,” she said. “There are probably multiple factors causing it, but we’ll also probably never know exactly what’s causing it.”
She said the causes stem either from seasonal changes to humans’ bodies that make it easier to conceive a child or changes in people’s behavior that increase the odds for pregnancy — or a combination of the two.
The phenomenon is important to study and it has real consequences, she said. If areas see particularly large increases in the number of babies being born at certain times, it can increase the odds for outbreaks of illnesses, particularly of childhood diseases.
(To see a full list of birthday dates and their popularity, click here.)
The three charts below show the most popular months (between Jan. and Dec.), the most popular days of the week (Sunday through Saturday), and the most popular day numbers within a month (between 1 and 31).
Advertisement
| Month | Rank | Average births per year | Days per month | Average births per day |
|---|---|---|---|---|
| August | 1 | 6,728 | 31 | 217.0 |
| July | 2 | 6,670 | 31 | 215.2 |
| June | 3 | 6,443 | 30 | 214.8 |
| September | 4 | 6,407 | 30 | 213.6 |
| May | 5 | 6,521 | 31 | 210.3 |
| April | 6 | 6,166 | 30 | 205.5 |
| October | 7 | 6,354 | 31 | 205.0 |
| March | 8 | 6,271 | 31 | 202.3 |
| February | 9 | 5,597 | 28.2* | 198.5 |
| November | 10 | 5,892 | 30 | 196.4 |
| December | 11 | 6,028 | 31 | 194.4 |
| January | 12 | 5,993 | 31 | 193.3 |
*February figure is adjusted to account for two Leap Years between 2005 and 2014.
SOURCE: Massachusetts Department of Public Health| Day of week | Rank | Births | Times weekday occurred, 2005-2014 | Average births per day |
|---|---|---|---|---|
| Friday | 1 | 119,907 | 521 | 230.1 |
| Thursday | 2 | 119,491 | 521 | 229.3 |
| Tuesday | 3 | 119,321 | 522 | 228.6 |
| Wednesday | 4 | 117,937 | 522 | 225.9 |
| Monday | 5 | 109,018 | 522 | 208.8 |
| Saturday | 6 | 87,660 | 522 | 167.9 |
| Sunday | 7 | 77,369 | 522 | 148.2 |
| Day number | Rank | Average births per year | Times date occurs annually | Average births per day |
|---|---|---|---|---|
| 15 | 1 | 2,508 | 12 | 209.0 |
| 7 | 2 | 2,503 | 12 | 208.6 |
| 19 | 3 | 2,502 | 12 | 208.5 |
| 14 | 4 | 2,500 | 12 | 208.3 |
| 21 | 5 | 2,499 | 12 | 208.2 |
| 18 | 6 | 2,497 | 12 | 208.0 |
| 3 | 7 | 2,491 | 12 | 207.6 |
| 8 | 8 | 2,490 | 12 | 207.5 |
| 9 | 9 | 2,490 | 12 | 207.5 |
| 17 | 10 | 2,489 | 12 | 207.4 |
| 22 | 11 | 2,483 | 12 | 206.9 |
| 29 | 12 | 2,317 | 11.2* | 206.9 |
| 10 | 13 | 2,482 | 12 | 206.8 |
| 6 | 14 | 2,474 | 12 | 206.2 |
| 11 | 15 | 2,472 | 12 | 206.0 |
| 28 | 16 | 2,470 | 12 | 205.9 |
| 12 | 17 | 2,469 | 12 | 205.8 |
| 16 | 18 | 2,467 | 12 | 205.6 |
| 2 | 19 | 2,458 | 12 | 204.9 |
| 30 | 20 | 2,252 | 11 | 204.7 |
| 1 | 21 | 2,456 | 12 | 204.7 |
| 27 | 22 | 2,454 | 12 | 204.5 |
| 20 | 23 | 2,452 | 12 | 204.4 |
| 23 | 24 | 2,452 | 12 | 204.4 |
| 5 | 25 | 2,447 | 12 | 203.9 |
| 31 | 26 | 1,423 | 7 | 203.2 |
| 24 | 27 | 2,437 | 12 | 203.1 |
| 4 | 28 | 2,429 | 12 | 202.4 |
| 26 | 29 | 2,409 | 12 | 200.8 |
| 25 | 30 | 2,408 | 12 | 200.6 |
| 13 | 31 | 2,391 | 12 | 199.3 |
*This figure for day number 29 is adjusted to account for two Leap Years between 2005 and 2014.
SOURCE: Massachusetts Department of Public Health(To see a full list of birthday dates and their popularity, click here.)
Matt Rocheleau can be reached at matthew.rocheleau@globe.com. Follow him on Twitter @mrochele