Many women hope for a birth around their baby’s due date. Find out here what happens if your baby is overdue and you are offered an induction of labour.
You feel like you’ve swallowed a whole watermelon and getting anywhere feels like a feat of Herculean proportions. Your baby must surely be ready to come out, right?
You’re not alone if you’ve been focusing on your due date throughout your pregnancy and counting down to it in the latter stages. And it’s understandable that you might feel disappointed or worried if you approach that date with no sign of your baby.
So when might you be offered treatment for a longer pregnancy and what happens? Well, the story starts with the due date…
When is a baby overdue or late?
Pregnancy normally lasts anywhere between 37 and 42 weeks, and that’s when it’s called a full-term pregnancy or term. An estimated due date, or EDD, is calculated as 40 weeks from the first day of your last menstrual period (Dekker, 2019).
A pregnancy that continues for longer than 42 weeks is called post-term, prolonged or overdue (Dekker, 2019). Over 80 in 100 babies arrive before 41 weeks of pregnancy and 99 in 100 arrive by 42 weeks of pregnancy (NICE, 2021). This may feel fine, or you may feel like you’ve had enough well before that date.
How accurate are due dates?
Estimates of the length of pregnancy are based on a woman having a menstrual cycle of 28 days. And because not everyone has that, and because we don’t all remember the date of our last period, ultrasound is considered more accurate at predicting pregnancy length (Reddy et al, 2014). An ultrasound can give an accuracy of plus or minus seven to 10 days (Reddy et al, 2014).
Why are some pregnancies longer?
We don’t fully understand why some pregnancies are shorter or longer, but we do know it can run in families (Oberg et al, 2013).
Longer pregnancies may be associated with first pregnancies, being older, having a boy and being heavier (Caughey et al, 2009; Oberg et al, 2013). Having African, Asian, or Latinx ethnic origins may make it less likely that you’ll have a longer pregnancy (Caughey et al, 2009).
Can I do anything to start labour myself?
For mums who’d prefer to have some control over the process, there are said to be some traditional ways of trying to induce labour at home. See more in our article about whether you can really kick-start your own labour or not.
What is induced labour?
Labour is a process that usually starts on its own. But sometimes labour will be started with the help of health professionals. This is called induced labour (NICE, 2021).
Find out more in our article about induction.
This page was last reviewed in September 2022.
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We also offer antenatal courses which are a great way to find out more about labour and life with a new baby.
Find out more about NICE guidance on the induction of labour
Caughey AB, Stotland NE, Washington AE, Escobar GJ. (2009) Who is at risk for prolonged and postterm pregnancy? AJOG. 200(6):683.e1-5. Available at: https://doi.org/10.1016/j.ajog.2009.02.034
Dekker R. (2019) The evidence on: due dates. Available at: https://evidencebasedbirth.com/evidence-on-due-dates/ [Accessed 27th September 2022]
NICE. (2021) Inducing labour [NG207]. Available at: https://www.nice.org.uk/guidance/ng207 [Accessed 27th September 2022]
Oberg A, Frisell T, Svensson A, Iliadou A. (2013) Maternal and fetal genetic contributions to postterm birth: familial clustering in a population-based sample of 475,429 Swedish births. Am J Epidemiol. 177(6):531-537. Available at: https://doi.org/10.1093/aje/kws244
Reddy UM, Abuhamad AZ, Levine D, Saade GR. (2014) Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. Am J Obstet Gynecol. 210(5):387-397. Available at: https://doi.org/10.1016/j.ajog.2014.02.028