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Third trimester

40 weeks pregnant

At 40 weeks 0 days to 40 weeks 6 days, you are still full term, which ACOG defines as 39 weeks 0 days to 40 weeks 6 days. Your due date falls at 40 weeks 0 days, but only a small share of babies arrive on that exact day. If labor hasn't started by the end of this week, your care team will talk with you about next steps.

This page covers 40 weeks 0 days to 40 weeks 6 days (40+0 to 40+6), counted from the first day of the last period. Check how far along you are

Enter it to see the calendar dates of your week 40.

Botanical illustration of a small watermelon

About the size of a small watermelon

Typical estimated weight 3.62 kg (8 lb 0 oz) at 40+0. This is the 50th centile; healthy babies commonly vary by about 12.7% either way.1

A reference value, not a measurement of your baby.

How your baby is developing

  • Your baby is getting quite squashed now, but should still move in their usual pattern. Movements should not slow down or stop before labor.2
  • By 40 weeks, about 38 weeks have passed since conception, because pregnancy is counted from the first day of your last period.3
  • Lanugo, the fine body hair from earlier in pregnancy, has mostly gone, apart from on the upper arms and shoulders in some babies.3
  • Your baby may still be coated in waxy vernix, or it may be mostly gone by the time they are born. Vernix helps protect the skin.4

Changes you may notice

Everyone’s experience is different. You may notice some of these, or none.

  • Practice contractions, called Braxton Hicks, are common now and should not be painful. Labor contractions hurt as your bump tightens, and the pain eases as the muscles relax.2
  • Feeling premenstrual, or having lower backache, can be early signs of labor.2
  • The early, latent phase of labor, when the cervix softens and starts to open, can take hours or sometimes days. You will probably be advised to stay at home during this time.5
  • If your baby's movements slow down, stop or change, contact your midwife or maternity unit straight away. Someone is there to answer calls 24 hours a day.2,6

Care around this week

  • UK: a 40-week antenatal appointment is usual if this is your first baby. Your blood pressure is checked, your bump is measured and your urine is tested for signs of pre-eclampsia. You may be offered a membrane sweep, which is usually offered after 39 weeks.2,7,8
  • UK: if labor has not started by 41 weeks, induction will be offered, and NICE guidance says to discuss induction from 41 weeks 0 days. US: MedlinePlus says your provider may not do anything until 41 weeks unless there are problems, and at 41 weeks will usually check on your baby with tests such as a non-stress test and a biophysical profile (an ultrasound check). Practice varies, so ask your own care team what they suggest.8,9,10
  • NHS advice is to call your midwife or maternity unit if you think you are in labor or contractions are coming every 5 minutes or more often. Call urgently if your waters break, you are bleeding, or your baby is moving less than usual.5

Questions to ask your provider

  • What is the plan if I don't go into labor this week?
  • When would you suggest induction for me, and why?
  • Would a membrane sweep be an option?
  • What checks will you do on my baby if I go past my due date?
When to contact your provider straight away

Call 911 (US) or 999 (UK) in an emergency, such as heavy bleeding or bleeding with severe pain, a seizure, chest pain, or severe trouble breathing.12,13,14,15

These symptoms are not always serious, but each one needs prompt advice from your provider, midwife or maternity unit (or NHS 111 in the UK if you cannot reach them) rather than waiting for your next appointment, and it helps to tell them you are pregnant.

  • Vaginal bleeding or spotting at any stage of pregnancy. Call 911 or 999 if the bleeding is heavy or comes with severe belly pain, shoulder pain, or feeling faint or dizzy.14,16
  • Fluid leaking or gushing from your vagina, or discharge that is unusual for you. Get checked straight away if the fluid is greenish, colored or smells bad.5,14,15,17
  • Your baby moving less than usual, not moving, or a change in their usual pattern of movements. Call immediately, even in the middle of the night, and do not use a home Doppler to check yourself.6,14
  • A severe headache that does not go away with simple painkillers or gets worse, or sudden changes in your vision such as blurring or seeing flashing lights.12,14,15
  • Sudden swelling of your face, hands or feet, or swelling, redness or pain in a leg.12,14,15
  • Belly pain that is severe or does not go away after resting, or pain just below the ribs.12,14,18
  • Regular tightenings or contractions, period-type pains, or backache that is unusual for you before 37 weeks, which can be signs of preterm labor.17,18
  • A fever of 100.4°F (38°C) or higher, or feeling hot, cold or shivery.14,15,17
  • Shortness of breath that comes on suddenly or happens when you lie flat, chest pain, a racing or pounding heart, or dizziness or fainting.14,15
  • Very itchy skin, especially on the palms of your hands or soles of your feet, or itching that is worse at night.19
  • Being sick so often that you cannot keep food or drink down, or signs of dehydration such as dark urine, peeing very little, or feeling dizzy.14,20
  • Thoughts of harming yourself or your baby. Get help right away, and call 911 or 999 if you think you might act on them.14,21

Questions about 40 weeks

What are the chances of giving birth on my due date?

Low. In an Australian study of 18,708 single babies born after labor started on its own, about 5% arrived on their estimated due date, and about two-thirds were born within 7 days of it.11

Are there natural ways to start labor?

There are no proven ways to start labor yourself at home. There's no evidence that things like hot baths, certain foods or herbal supplements work, and herbal supplements may not be safe. Ask your midwife or doctor before trying anything.2,8

How likely is labor to start this week?

In NHS data from 2019 to 2020, about a third of labors that started on their own began between 40 weeks 0 days and 40 weeks 6 days. By the end of this week, about 83% of them had started.9

Sources

  1. In utero analysis of fetal growth: a sonographic weight standardRadiology 181(1):129–133, 1991
  2. Week 40NHS Best Start in Life
  3. Fetal developmentUS National Library of Medicine
  4. Week 39NHS Best Start in Life
  5. Signs of going into labourNHS Best Start in Life
  6. Your baby's movementsNHS (England)
  7. Your antenatal appointmentsNHS (England)
  8. Inducing labourNHS (England)
  9. Inducing labour (NG207), table 1National Institute for Health and Care Excellence, 2021
  10. When you pass your due dateUS National Library of Medicine
  11. Predicting date of birth and examining the best time to date a pregnancyInternational Journal of Gynecology & Obstetrics 123(2):105–109, 2013
  12. Pre-eclampsiaNHS (England)
  13. Epilepsy and pregnancyNHS (England)
  14. Urgent Maternal Warning Signs and Symptoms (Hear Her campaign)US Centers for Disease Control and Prevention
  15. Pregnancy symptoms you need to get help forNHS (England)
  16. Vaginal bleeding in pregnancyNHS (England)
  17. Premature labour and birthNHS (England)
  18. Stomach pain in pregnancyNHS (England)
  19. Itching in pregnancyNHS (England)
  20. Severe vomiting in pregnancyNHS (England)
  21. Depression in pregnancyNHS (England)

Links checked November 12, 2026. Citing a source does not mean it endorses this site.

Written from the sources above and checked against them on 2026-11-12. Not reviewed by a clinician. Our editorial policy