What is the rarest birthday month?
The rarest month to be born is February. Since it’s the shortest month with only 28 days (or 29 during a leap year), there are fewer days to count. Just under 271,000 babies arrived in February 2023 – that’s 51,000 fewer babies than arrived in August of that same year. April is the next most uncommon month to be born – about 279,000 babies were born in April 2023 in the U.S.
Unsurprisingly, February 29 is the most uncommon birthday in the U.S., since it officially only happens once every four years. There is a 1 in 1,461 chance of being born on February 29 – and less than 0.1% of the world’s population has that birthday!
The rarest birth months in the U.S. (2023)
- February
- April
- December
- November
- March
- January
- May
- June
- September
- October
- July
- August
Why is there a most common month to be born?
There are several theories about why there is a most common birth month, ranging from biological to cultural. And with August and July being the most common birth months, that means winter is a good time to make babies – November and December are the most popular months to conceive.
Research has suggested male fertility is higher in colder months, with improved sperm quality. Some think there’s also an evolutionary drive for humans (and other species) to conceive in the winter and give birth in the spring or summer. Also, cold weather encourages couples to spend more time together indoors, which can lead to more opportunities for intimacy. Add in the holiday season, parties, extra time off of work, and more time with family and you can see how nine months later there will likely be a baby boom!
For healthy couples in their 20s and early 30s, around 1 in 4 women will get pregnant in any single menstrual cycle, according to the American College of Obstetricians & Gynecologists. So even if everything is perfect, pregnancy is still not achieved most of the time. But don’t be discouraged! On average, 85% of healthy couples under age 35 conceive within one year. However, choosing the exact month you’re aiming for could be trickier than you think.
“Some of our patients are trying to plan the month they get pregnant and we support them every way we can, but this can be hard to do,” said Dr. William Thompson III, gynecologic surgeon and obstetrician, at Allina Health. “Sometimes pregnancy happens on the first try, or it might take a year or more. In some instances, pregnancy requires treatments with a fertility specialist. We want all our patients to feel supported and hopeful throughout their journey with us and know they have received the best care – whatever month their baby arrives.”