The surprising truth about when your baby will arrive (hint: probably not on your due date)
From late-night contractions to September baby booms, here’s what the data really says.
You’ve known your due date for months, but had your hospital bag packed for three weeks because you never know when baby will come — right? There’s lots of data on when babies are more likely to be born, so although there’s no way of knowing exactly when you’ll get to meet your baby, you can make a good guess.
From the specific time, day, and month, we’ve outlined when your baby is most likely to be born — plus why you shouldn’t assume your due date is accurate.
Due dates are a helpful suggestion
Despite doctors giving you a due date, very few babies actually arrive on that specific day. Data varies, but only about 5% of babies are born on their due date. Most babies are born within two weeks either side of their due date, with some arriving a little earlier or later.
Due dates aren’t an exact science. Doctors add 280 days to the date of your last period, but this has to be an estimate because not everyone’s menstrual cycles are 28 days long, not everyone ovulates on the 14th day, and we can’t know exactly which day conception occurred. Due date tends to be more accurate where we can know the date of ovulation, such as when mums use IVF or fertility tracking.
But you don’t need to worry too much about your baby being a few weeks or days early or late. Hospitals tend to recommend a membrane sweep to encourage labour after 39 weeks, or an induction if you haven’t gone into labour by 41 weeks. It’s rare that pregnancies will last more than 42 weeks.
What this means for your labour:
You can’t control when your baby comes if you aren’t having a pre-planned Caesarean section, so try to be flexible and ready for anything from a few weeks before your due date. The NHS recommends having your hospital bag ready to go from three weeks before your due date.
Babies are most likely to be born at night
A 2018 study by researchers at University College London and the National Childbirth Trust found that more than half of non-induced births happen between 1am and 7am, with 4am being the most popular. Only 28% of births happened between 9am and 5pm on a weekday.
This isn’t because babies want to be respectful of working hours, but, researchers suggest, because of our evolutionary biology — Dr Peter Martin, the lead author of the study, told UCL that early humans came together to rest at night, meaning there was more protection for the mother and newborn. Other factors could include higher levels of the hormone melatonin at night, since a 2020 study by researchers at Harvard found links between higher concentrations of the hormone and increased uterine contractions.
However, if you’re having an elective or pre-planned Caesarean section, that will most likely be between 9am and 12pm on weekdays, since they can be scheduled in advance.
What this means for your labour:
Be prepared to get to the hospital at any time of day or night and have snacks in your hospital bag in case there’s no food available overnight.
September is the most popular birth month at the moment
In the UK, September is the most popular month for babies to be born, according to analysis of data from the Human Mortality Database by Our World In Data. However, this changes over time — for example, July was the most popular month for babies to be born in 2013.
This could be because people are most likely to conceive in the winter months, when everyone is cold and spending more time inside more. There’s also the widely believed idea that children born earlier in the school year do better, although recent studies have suggested that this isn’t always true.
What this means for your labour:
Depending on when your baby comes, the hospital might be busier with other mums giving birth. But this isn’t anything to worry about since hospitals should have procedures in place to deal with this.
Babies don’t respect public holidays
Babies will arrive when they are ready, whether it’s a major holiday or not. They are just as likely to be born on Christmas Day, New Year’s Day, or any other holiday as on any other day of the year. (Although according to data from the Office for National Statistics, fewer babies tend to be born on Boxing Day than on Christmas Day.)
What this means for your labour:
If you are due around a national celebration or bank holiday, it’s worth being extra prepared, as there may be changes in hospital staffing and opening hours for pharmacies and shops.