Week 40 is the week your pregnancy has been counting towards. Reaching 40 weeks pregnant means you have arrived at your estimated due date, the milestone circled on the calendar since your very first scan. It is an exciting, and often impatient, time as you wait to meet your baby at last.
It helps to remember that a due date is an estimate rather than a deadline. Only a small proportion of babies arrive exactly on the date they are given, and many first-time mothers go slightly beyond it. Whether labour begins this week or you find yourself waiting into week 41, understanding what is happening can make these final days feel calmer and more manageable.
Your baby at week 40
By 40 weeks your baby is fully developed and ready to be born. At this stage a baby is typically around 50 centimetres in length from head to heel and weighs somewhere in the region of 3.4 kilograms, though there is a very wide and completely normal range. Some healthy babies are noticeably smaller or larger than this, and size alone tells you little about how labour will unfold.
Your baby's organs are mature and working in preparation for life outside the womb. The lungs are ready to take their first breath, and the digestive system is primed to begin feeding. The soft, downy hair known as lanugo has largely disappeared, and the vernix that protected the skin has mostly been absorbed, though some may remain at birth.
Most babies have settled into a head-down position ready for delivery by now. Space inside the uterus is limited, so movements often feel more like squirms, rolls and pressure than the sharp kicks of earlier weeks. Importantly, your baby should still move regularly right up until labour and birth. If you notice any change in the pattern or frequency of movements, contact your maternity unit straight away rather than waiting.
Your body at week 40
The final week of pregnancy can bring an intense mix of physical sensations as your body prepares for labour. Many of these are entirely normal, even if they feel new or uncomfortable.
- Braxton Hicks and practice contractions. These tightenings can become stronger and more frequent as your due date approaches. They are usually irregular and ease off, unlike the building pattern of true labour.
- Pelvic pressure and lightening. As your baby's head engages deeper into the pelvis, you may feel increased pressure low down, along with easier breathing as the bump drops.
- Backache and period-type cramps. A dull, aching lower back and mild cramping are common as ligaments soften and the cervix begins to change.
- Changes in vaginal discharge. Some women notice a thicker discharge or the passing of the mucus plug, sometimes called a "show", which can appear pink or lightly blood-tinged.
- Broken sleep and fatigue. Frequent trips to the toilet, a heavy bump and anticipation can all disrupt rest in these final nights.
Some symptoms need prompt attention rather than watchful waiting. Contact your midwife or maternity unit without delay if you experience heavy or bright red bleeding, severe or constant abdominal pain, a sudden reduction in your baby's movements, a bad headache with visual disturbance or swelling, or if your waters break, particularly if the fluid is green, brown or bloodstained.
What to keep in mind this week
Knowing the signs that labour is starting can help you feel more in control. According to NHS guidance, the key signs to look out for include regular contractions that grow longer, stronger and closer together, a "show", backache, and your waters breaking. Early labour can take time to establish, and staying at home resting, eating and sleeping is often encouraged until contractions become regular.
A few practical steps for this week:
- Keep your hospital bag packed and ready, along with your maternity notes.
- Make sure you know who to call and when, and keep those numbers to hand.
- Rest when you can and stay gently active, as movement and upright positions can help.
- Keep hydrated and eat regularly to maintain your energy for labour.
- Continue to monitor your baby's movements and report any change promptly.
If your pregnancy reaches 41 or 42 weeks, your midwife or obstetrician will typically discuss your options with you, which may include a membrane sweep or induction of labour. These conversations are individual, and your maternity team will explain what is recommended for your circumstances.
Scans, tests and appointments
By week 40 the routine NHS screening milestones are behind you. The 20-week anomaly scan takes place at 18 to 21 weeks, the glucose tolerance test (if offered) at 24 to 28 weeks, the whooping cough vaccine between 16 and 32 weeks, and RSV vaccination is offered from 28 weeks. Around this stage of the third trimester, your team may also discuss group B streptococcus if it is relevant to you.
Your antenatal appointments continue, with your midwife checking your blood pressure, urine, bump measurement and your baby's position and heartbeat. At London Pregnancy Clinic, we also offer additional scans that some parents find reassuring in these final days. A presentation scan confirms whether your baby is head-down, breech or in another position, which can be useful information as you approach labour. A reassurance scan can check your baby's wellbeing, growth and amniotic fluid if you would value extra peace of mind while you wait.
It is also worth looking a little further ahead. Our postnatal support ahead is designed to care for you and your baby in the weeks after birth, so you can put arrangements in place now. And if you would like a personalised view of the milestones you have passed and those still to come, our pregnancy journey planner maps your timeline week by week.
Looking ahead
Reaching your due date is a remarkable achievement, whether your baby arrives this week or takes a little longer. If you have already read our guide to week 39, you will know how much anticipation these last days can hold. Should your pregnancy continue, week 41 covers what to expect when your baby is comfortably taking their time.
Try to rest, stay in close contact with your maternity team, and trust that your body and your baby are preparing for the moment you have been waiting for. The finish line is very close now.
This article is for general information only and is not a substitute for professional medical advice. Always speak to your midwife, GP or obstetrician about your own pregnancy.
