# 40 Weeks Pregnant: Baby Size, Symptoms & What to Expect | Clever Mum

> 40 weeks pregnant — your baby is the size of a small pumpkin. What's developing, what you might feel, and what to focus on this week.

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Third trimester

 
#  40 weeks pregnant

 

Your baby is about the size of a small pumpkin 

   [ CP ](/authors/parenting-desk/)  
 By [ Clever Mum Parenting ](/authors/parenting-desk/) · Parenting guides 

 
 Published 11 July 2026  

      
 
Quick answer — What happens at 40 weeks pregnant? 

 
At 40 weeks pregnant, your baby is about the size of a small pumpkin, roughly 51.2cm and around 3500g. Your due date.

    
Who should skip this

 
Skip this page if you need personal medical advice — it is general NHS-aligned information, not a substitute for your midwife. If your baby's movements slow or change, call your maternity unit, not a website.

    
## How big is the baby at 40 weeks pregnant?

 
At 40 weeks pregnant, your baby is about the size of a small pumpkin, roughly 51.2cm and around 3500g. Your due date. The average newborn is around 51cm and 3.5kg, but there's a wide healthy range. The baby is ready to meet you — birth happens when they and your body are ready. These are typical averages — your midwife's measurements are the ones that matter for your pregnancy.

 
## What might you feel at 40 weeks?

 
Most people at 40 weeks notice some mix of the symptoms below — and plenty notice none of them. Going past your due date is completely normal. Your midwife will discuss monitoring and, if needed, options for induction, usually offered around 41–42 weeks. None of this is a diagnosis; contact your midwife if something worries you.

  
### Common symptoms this week

 
 * Due date arrives (only ~1 in 20 babies come on theirs)
* Pressure, tightenings and impatience
 
 

Symptom lists are typical, never exhaustive — and having none of them is normal too.

  
## What should you do at 40 weeks pregnant?

 
The useful job this week is practical, not medical. Discuss what happens if you go overdue with your midwife — you may be offered a membrane sweep from around now to help things along naturally. Pair it with the NHS week-by-week guide if you want a second description of the same stage.

    
### Week 40 checklist

 
 * Attend your 40-week appointment (first babies)
* Consider the membrane sweep if offered
* Ask your unit how post-dates monitoring works
 
   
## What else is useful at 40 weeks?

 

Use the week page for size and symptoms; use the guides below for the decisions that
                actually sit in this window — pay, packing, car seats, labour signs.

 
 *  [Due date calculator](/tools/due-date-calculator/) 
*  [Trimester to-do list](/pregnancy/pregnancy-to-do-list-by-trimester/) 
*  [Maternity leave and pay](/pregnancy/maternity-leave-and-pay-uk/) 
*  [Best infant car seats](/best/best-car-seats-uk/) 
*  [Hospital bag checklist](/pregnancy/hospital-bag-checklist-uk/) 
*  [Signs of labour](/pregnancy/signs-of-labour-what-to-expect/) 
 
    
## 40 weeks pregnant: common questions

    What is a membrane sweep?   
 A midwife sweeps a finger around the cervix during an internal examination to separate the membranes, releasing hormones that can trigger labour — offered from around 40 weeks (sometimes 39 for second babies). It's brief, can be uncomfortable, and makes labour within 48 hours more likely for many. 

   How big is my baby at 40 weeks pregnant?   
 At 40 weeks, your baby is approximately the size of a small pumpkin, about 51.2cm and around 3500g. These are approximate averages — every baby grows at its own pace. 

   What's happening at 40 weeks pregnant?   
 Your due date. The average newborn is around 51cm and 3.5kg, but there's a wide healthy range. The baby is ready to meet you — birth happens when they and your body are ready. For you: going past your due date is completely normal. your midwife will discuss monitoring and, if needed, options for induction, usually offered around 41–42 weeks. 

   Which trimester is 40 weeks?   
 40 weeks pregnant is in the third trimester. The first trimester runs to the end of week 12, the second from weeks 13 to 26, and the third from week 27 to birth. 

     
## 
Sources & further reading

 
 *  [ You and your baby at 4 to 40 weeks pregnant ](https://www.nhs.uk/pregnancy/week-by-week/)  — NHS 
*  [ Your baby's movements ](https://www.nhs.uk/pregnancy/keeping-well/your-babys-movements/)  — NHS 
 
   [← 39 weeks](/pregnancy/week/39/) [All weeks](/pregnancy/week/) [41 weeks →](/pregnancy/week/41/)  

This is general information, not medical advice — every pregnancy is different. For
          anything that worries you, and for all your antenatal care, speak to your midwife or GP.
          If your baby's movements ever slow down or change, contact your maternity unit
          immediately, day or night. Reviewed August 2026.

    
## Week 40 at a glance

   Trimester Third trimester  Baby size small pumpkin  Approx length ~51.2cm  Approx weight ~3500g  Weeks to go 0 (to 40)     
Work out your dates

 

Not sure how many weeks you are? Our
[due date calculator](/tools/due-date-calculator/)
maps your weeks and trimester dates from your last period.