How Popular is Your Due Date?

How Popular is Your Baby’s Due Date?

When you first find out that you’re pregnant, there are so many exciting new experiences to look forward to and so much information to learn. Depending on the time of year, you might need to purchase newborn summer or winter outfits; you might like to prepare a Christmas gift for a baby born in early December; or you might even be wondering about what school year your little one will fall into.

One of the first things you’ll be wondering when you learn you’re pregnant is: when is my baby due? You’ll probably have a good idea yourself as soon as you’ve taken a pregnancy test, but your first appointment with a midwife or health professional will help you confirm it.

[Post updated April 2026]

Calculating the Big Day

Did you know that the estimated length of pregnancy not only differs from person to person, but also by culture? Where in the UK we tend to say pregnancy lasts 9 months or 40 weeks, in France, medical professionals consider it to be 41 weeks. Some even question whether pregnancy is 10 months long!

Even though these are the suggested average pregnancy lengths, we all know that a due date isn’t 100% accurate. In fact, it can be far from it! Figures from the Perinatal Institute show that only 4% of babies are born on their due dates! Any time between 37 and 42 weeks is considered full term for a normal, single pregnancy. This means that, even if you and a friend have the same due date, your babies could be born over a month apart!

Is There a “Baby Boom” Specific Time?

No matter when your baby is due, there will be a few preparations you’d like to take. But are there certain dates that are more popular than others for babies to be born? Current trends suggest a resounding yes!

Using health statistics and national statistics sourced from the Office for National Statistics (ONS) on babies born over the last two decades, Smart Cells has updated the data for 2026. The visualisation of this data clearly shows that there is a most popular birthday month, and a few dates that are far less common.

The 10 Most Popular Birth Dates in the UK

According to the most recent data on the highest number of births, the end of September and early October dominate the rankings. If your baby due date falls in late September, they will be sharing a birthday with a lot of peers!

Why is September the Most Popular Birth Month?

Those who have spotted their own dates of birth in the top 10 will likely already know the reason experts suggest for this: Christmas! Counting back 39 weeks (the average gestation from a single menstrual cycle) from late September leads us directly to the annual Christmas holidays. Bank holidays, time off from work, and festive celebrations provide more specific time for couples to conceive.

Beyond just having extra time, studies suggest that sperm quality is often higher during the winter months compared to the summer months. The cold weather may actually assist in conception rates. In contrast, late summer and the following summer months often see a slight dip in conception, perhaps due to the heat affecting biological factors.

The “School Year” Advantage

Not only are the celebrations of December credited for the popularity of September births, but parent planning may also play a role. With data suggesting that children born early in the academic school year fare better than their younger peers (the “August babies”), it’s likely that some parents try to aim for their child to be born in September or early October. This timing also means women in labour avoid the most taxing heat of the summer months.

The 10 Least Common Birthdays in the UK

The rarest birthdays almost exclusively fall on major holidays. This is largely because medical professionals generally do not schedule elective C-sections or inductions on bank holidays. The heightened stress at these times of years may also contribute to the release of stress hormones which isn’t optimal for your body going into labour.

1. 26th December (Boxing Day) – The least popular birth date.
2. 25th December (Christmas Day) – Consistently low numbers.
3. 1st January (New Year’s Day)
4. 27th December
5. 24th December (Christmas Eve)
6. 2nd January
7. 13th April (Often falls near Easter)
8. 1st April (April Fools’ Day)
9. 28th December
10. 30th November

The figures show that there are approximately 45% fewer babies born on Boxing Day than on the 26th September. Spontaneous births still happen on these days, of course, but the “planned” element of modern maternity care significantly shifts the numbers away from the festive period.

What About Leap Year?

Technically, February 29th has the lowest total number of births over any 20-year period because it only occurs once every four years. However, when you look at the average number of births on the days it does occur, it actually ranks as a fairly average day for deliveries.

Comparing the UK to the United States

Interestingly, popular birthdays differ slightly across the pond. According to the Social Security Administration in the United States, September 9th is often cited as the most common birthday, followed closely by September 19th. While the “September peak” remains consistent due to the holiday season, the specific date shifts slightly. The U.S. also sees a dip during their own major holidays, such as Independence Day and Thanksgiving, for the same reasons we see a dip on Boxing Day in the UK.

Celebrities Born on the Most Common Birthday (26th September)

If your birthday or your baby’s due date falls on 26th September, the most common birthday in the world, you are in famous company!

• Serena Williams (Tennis Legend)
• Adam Sandler (Actor and Comedian)
• Olivia Newton-John (Singer/Actress)
• T. S. Eliot (Poet)
• Christina Milian (Singer)

Frequently Asked Questions

Is my due date a good guess of when the baby will arrive?

It is a good guess, but only a guess! Only 4% of babies arrive on their specific date. Most medical professionals consider a healthy pregnancy to be anything from 37 to 42 weeks.

Why is the 26th of September the most popular day?

It falls exactly 39 weeks and 2 days after Christmas Day. Given that many people have time off and are celebrating, it is the peak time for conception.

What is the rarest birthday (excluding Leap Day)?

In the UK, the rarest birthday is consistently December 26th (Boxing Day).

Do menstrual cycles affect these statistics?

While individual menstrual cycles vary, these broad statistics are based on thousands of births, which smooths out individual variations to show clear seasonal trends in sperm quality and frequency of intercourse.

This article is for informational purposes only. For specific medical advice regarding your pregnancy, please consult your healthcare provider.