Pregnancy Due Date Calculations – How Many Babies Arrive on Time?

The normal term of a pregnancy is classed as 40 weeks. Midwives and doctors calculate a pregnancy due date as 280 days from the first day of the last period. This means that by the time most women are alerted that they are having a baby (from the day of a missed period) they would already be classed as being 4 weeks pregnant.

But how many babies actually arrive on time? The EDD (meaning estimated due date) given to pregnant women is classed as a guide, as the actual length of a pregnancy can vary because of different people’s ovulation patterns and the fact that the date of fertilisation is rarely known accurately.

We conducted a poll amongst over 300 members to find out how accurate the pregnancy due date they were given turned out to be.

Bang on time
General statistics report that only 5% of babies are born on their EDD but our members had much more success. Over 14% stated that their baby was born on the date they were given. Most mums had a sense of achievement at this:

“Zoe arrived on her due date: I was a very proud mummy.”
“Kiera arrived on her due date too, who says girls are always late!”

Early babies
Going into labour early can be a worry for many mums-to-be, but a pregnancy is classed as full term at 37 weeks. The majority of babies are born two weeks either side of their due date so if your little one is slightly early there is usually no need for concern.

Our survey showed that of our members who responded, 34% had their babies before their EDD. The majority were within the normal 2 week window, but there were a few exceptions of babies arriving very early and now doing well:

“These 2 were 10 weeks early” – mums of multiple births report a higher percentage of their babies being born early.
“2nd was 14 weeks early” – our mums told us about their healthy, bouncing premature babies.

Late arrivals
Nearly 51% of our respondents reported that their babies arrived later than their EDD. Whilst it may be frustrating to have to wait a bit longer, babies being born past their due date is completely normal. Your doctor and midwife will monitor you and if you continue into your overdue pregnancy without any signs of your baby making a move, then they may decide to induce you.

“My pregnancy lasted 42 weeks exactly and ended up having a c-section as he was not coming out … he was too comfy!!”

So whilst your pregnancy due date is a good guide for when to expect your new arrival it’s clear to see that babies will come when they are ready! If you’d like to find out roughly when your baby is due, try our pregnancy due date calculator.