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40 Weeks Pregnant: Your Due Date Arrives

Medically reviewed by

Verena Brehm, Midwife Jul 29, 2026

Line illustration of a watermelon cut in half: at 40 weeks pregnant your baby is about the size of a watermelon

Line drawing of a full-term 40-week baby curled head-down with one hand up by the cheek, ready to be born

Line drawing of a woman's torso at 40 weeks pregnant, turned slightly to one side, showing the uterus inside a full-term bump

Your baby is the size of a

Watermelon

~3,400 g

~36 cm / ~14.2 in

Key Takeaways

At 40 weeks pregnant, your baby is fully developed. According to Mayo Clinic, your baby might have a crown-to-rump length of around 360 millimetres and weigh about 3,400 grams — and healthy babies come in lots of sizes.

Your due date is an estimate, not a deadline. Only around 4 in 100 babies actually arrive on the day itself, and SOGC notes that many women deliver before their due date just as many carry beyond it.

Movement still matters right up to birth. SOGC advises that if you don't feel 6 movements in 2 hours, you should contact your health care provider as soon as possible.

Your Baby at 40 Weeks: Development & Growth

At 40 weeks pregnant, your baby is fully developed. According to Mayo Clinic, at week 40 your baby "might have a crown-to-rump length of around 14 inches (360 millimeters) and weigh about 7 1/2 pounds (3,400 grams)" — though Mayo is quick to add that "healthy babies come in lots of sizes." The building is done; your baby is simply ready.

Your baby is about 36cm this week, measured crown to rump, and around 3,400 grams. Mayo Clinic puts it as a "crown-to-rump length of around 14 inches (360 millimeters)" and a weight of "about 7 1/2 pounds (3,400 grams)." Even at full term, Mayo still gives this length crown to rump, not the full head-to-heel measurement.

Size varies more than a single number suggests. Mayo Clinic adds simply, "remember that healthy babies come in lots of sizes." A baby a little smaller or a little larger than average is still exactly where they should be.

The developmental work finished weeks ago. Mayo Clinic notes that by week 39 your baby "is considered full term," with fat "being added all over the body to keep your baby warm after birth." By now, your baby is a finished, ready newborn waiting for the signal to arrive.

And that signal comes on its own schedule. Only about 4 in 100 babies are born on the date itself. Mayo Clinic reassures, "Don't be worried if your due date comes and goes with no signs of labor starting... Many people give birth before or after their due dates." The estimate has done its job; the timing is your baby's.

Your Body at 40 Weeks: Symptoms & Changes

At 40 weeks pregnant, your body is doing the quiet work of the final days — and often signalling that labour is near. SOGC lists the early signs: the baby dropping lower into your pelvis, a change in vaginal discharge as the mucus plug releases, and irregular contractions that gradually become regular. Fatigue and the other discomforts of pregnancy linger too, and they land harder now. Every pregnancy is different.

Some of the earliest signs of labour are subtle. SOGC explains that in the last weeks "the baby will 'drop'" — the head descends into your pelvis, so "your belly looks lower, your breathing is a bit easier, but your need to urinate increases." For some, this happens only just before labour.

Another sign shows up as discharge. SOGC notes that in the last several days "your vaginal discharge may change as the mucus plug that has sealed your cervix releases," which "will look like a brownish or bloody discharge." It is a normal part of the cervix getting ready.

Contractions are the sign most mothers are watching for. SOGC says you "may have irregular, periodic contractions," and that "once your contractions are happening every 5 minutes or less, it is usually an indication that labour is beginning." A convenient guide, SOGC adds, "is to wait until there have been at least 10 contractions in an hour."

The everyday discomforts can carry on to the finish line. SOGC lists fatigue, backaches, headaches, constipation, leg cramps and mood swings among the common symptoms of pregnancy, and reminds us plainly that "every pregnant woman is different." Whatever your last week looks like, it is temporary.

If this feels like the hardest week yet, that is not a failure of attitude. Fatigue is on SOGC's list for a reason, and at 40 weeks it compounds: sleep is broken, the bump is at its heaviest, and waiting past a date you have counted toward for months carries its own weight. There is nothing left to prepare that is more useful than rest. Take the naps. Say yes to the help.

Headaches deserve a second look, even now. Most come from the obvious places — a bad night, a tense neck, not enough water. But SOGC names "headaches, blurred vision, dizziness, nausea or vomiting, or shortness of breath" among the symptoms to watch for with preeclampsia, a complication it describes as "marked by high blood pressure and the presence of protein in the urine." Preeclampsia does not stop being possible because you have reached your due date. Severe, unshifting, or arriving with vision changes or sudden swelling — call.

What to Do at 40 Weeks Pregnant

NUTRITION AT 40 WEEKS PREGNANT

Keep eating well and regularly — labour is physical work. There is no special "due date" diet, but steady, balanced meals help you keep your energy up while you wait. Small, frequent meals and snacks are easier than large ones now: there is very little room left, digestion is slower, and hunger comes back sooner than it used to.
Stay hydrated. Drink to your thirst through these final days; it supports the extra blood volume your body is still carrying and helps with the constipation and swelling that can linger right to the end.
Keep caffeine to 300mg a day. Health Canada recommends a maximum daily caffeine intake of 300 mg for people who are pregnant, and puts one 8oz (237ml) cup of brewed coffee at about 135mg — so roughly two cups is the ceiling, and that total includes tea, cola and chocolate.

WHAT SUPPLEMENTS TO TAKE AT 40 WEEKS PREGNANT

Keep taking your 400mcg of folic acid. The Public Health Agency of Canada states that "a daily multivitamin with 400 mcg (0.4 mg) of folic acid is recommended for anyone who could become pregnant," and advises: "Continue taking folic acid throughout your pregnancy and while breastfeeding" — so it doesn’t stop at the due date.
Don’t raise your folic acid dose on your own. The Public Health Agency of Canada advises: "You should not increase your dose of folic acid beyond 1 mg per day without talking to your health care provider." A higher dose is a conversation, not a decision for the supplement aisle.
Keep any other prenatal supplements going as prescribed. If your provider has you on iron, vitamin D or a prenatal vitamin, there is no reason to stop now — carry on until they advise otherwise.

LIFESTYLE TIPS AT 40 WEEKS PREGNANT

Know your contraction guide before you need it. SOGC advises that "once your contractions are happening every 5 minutes or less, it is usually an indication that labour is beginning," with "at least 10 contractions in an hour" as a convenient marker. Have your provider’s number and your hospital bag ready.
Expect a slow start. SOGC calls the first part of labour the latent phase and describes it as "the longest stage of labour" — "irregular, increasingly frequent contractions" that thin and open the cervix to about 4 cm, and through which, in a healthy term pregnancy, "you will typically be at home." It can take many hours. That is the beginning working, not stalling.
Understand what happens when your water breaks. SOGC notes that "if your water breaks and you are at term, your health care provider may offer or recommend induction of labour." Call your provider when it happens, and note the time, colour and amount. If you are not sure whether it has broken, keep the pad or underwear you were wearing and take it with you — the fluid can be tested to confirm.
Keep noticing your baby’s movements. SOGC says "your perception of your baby’s movements is one of the strongest indicators of your baby’s wellbeing," and that movement awareness matters "especially in the third trimester" — right up to birth. Count everything, not only kicks: SOGC counts "kicks, flutters, or rolling movements."
Rest when you can, and move gently when you can’t settle. Walking is fine if you feel up to it, but there is no need to force labour along; the aim this week is to stay rested and ready.

When to Contact Your Doctor or Midwife

Most of week 40 is waiting, not worry. But some signs need a call or a trip to the hospital, and this is the week to know them cold. Contact your doctor, midwife or other health care provider if you experience:

A change in your baby's movements, or fewer movements than usual. Movement matters right up to birth. SOGC advises: "To do a kick count, count the baby's movements for 2 hours. If you don't feel 6 movements (such as kicks, flutters, or rolling movements) in 2 hours, you should contact your health care provider as soon as possible." SOGC adds that mothers "should always trust their intuition." Do not wait this out.
Signs of preeclampsia. SOGC names "headaches, blurred vision, dizziness, nausea or vomiting, or shortness of breath" among the symptoms to watch for, in a complication it describes as "marked by high blood pressure and the presence of protein in the urine." Sudden swelling of the face, hands or feet belongs on that list. Reaching your due date does not rule it out — call the same day.
Regular contractions that signal labour. SOGC explains that "once your contractions are happening every 5 minutes or less, it is usually an indication that labour is beginning," with "at least 10 contractions in an hour" as a convenient guide. Follow the plan your provider has given you for when to come in.
Your water breaking. SOGC notes that "if your water breaks and you are at term, your health care provider may offer or recommend induction of labour." Contact your provider when it happens, and note the time and the colour of the fluid — greenish or brown fluid should be reported straight away, as it can mean the baby has passed meconium. If you are unsure whether your water has broken at all, bring the pad or underwear you were wearing so the fluid can be tested.
Any vaginal bleeding beyond the normal bloody show. A brownish or bloody discharge as the mucus plug releases is expected, per SOGC. Fresh or heavier vaginal bleeding is not — contact your provider promptly, and if bleeding is heavy or you feel very unwell, seek emergency medical care immediately.
Passing your due date. If you reach or pass your due date without labour starting, contact your provider to confirm the plan for monitoring. SOGC notes that "a pregnancy that had gone more than 10 days beyond the due date is called 'post-dates'," and your care team will want to keep an eye on your baby from here.

Frequently Asked Questions

How big is my baby at 40 weeks pregnant?

At 40 weeks pregnant, your baby is fully developed. According to Mayo Clinic, at week 40 your baby "might have a crown-to-rump length of around 14 inches (360 millimeters) and weigh about 7 1/2 pounds (3,400 grams)" — roughly 36cm crown to rump and 3,400 grams. Mayo Clinic adds that "healthy babies come in lots of sizes," so a baby a little smaller or larger is still perfectly normal. Even at full term, Mayo gives this length crown to rump rather than head to heel.

Do many babies actually arrive on their due date?

Very few — only around 4 in 100. Your due date is a calculation, not a prediction: Mayo Clinic explains that it "is simply an estimate of when your pregnancy will be 40 weeks along," counted ahead 40 weeks from the start of your last period, and that "it doesn’t predict exactly when your baby will arrive." The Society of Obstetricians and Gynaecologists of Canada (SOGC) puts it the same way — due dates "are only estimates of when delivery may occur," and "many women deliver their babies before their due date just as many women will carry their pregnancy beyond their due date."

Why do I feel so exhausted at 40 weeks?

Because this is the heaviest and most demanding point of the whole pregnancy. Fatigue is on the Society of Obstetricians and Gynaecologists of Canada’s (SOGC) list of common pregnancy symptoms, and at 40 weeks it stacks up: broken sleep, pressure on your bladder, a body carrying its maximum load, and the particular tiredness of waiting past a date you have counted toward for months. SOGC also reminds us that "every pregnant woman is different" — some feel reasonably well to the end, others feel every day of it. Rest is genuinely the most useful thing left on your list.

What does it mean if I go past my due date?

Your due date is only an estimate. The Society of Obstetricians and Gynaecologists of Canada (SOGC) explains that due dates "are only estimates of when delivery may occur," and that "many women deliver their babies before their due date just as many women will carry their pregnancy beyond their due date." SOGC notes that "a pregnancy that had gone more than 10 days beyond the due date is called ‘post-dates’," and reassures that "usually an overdue baby is born healthy." Your provider will step up monitoring while you wait.

How is my baby monitored if I go overdue?

The Society of Obstetricians and Gynaecologists of Canada (SOGC) explains that your health care provider "will likely recommend daily kick counts and may suggest non-stress tests (checking the baby’s heart rate) twice weekly, or that you have your amniotic fluid volume assessed by ultrasound." These checks confirm your baby is still healthy while you either wait for labour to begin naturally or plan an induction.

When is induction discussed if I’m overdue?

The Society of Obstetricians and Gynaecologists of Canada (SOGC) explains that after your due date you can "decide to wait for labour to begin naturally with or without enhanced testing," or "decide to have your labour induced." SOGC notes that "current research shows that induction at 41 to 42 weeks is safer for the baby than a ‘watch and wait’ approach, and does not result in an increased risk of Caesarean section." It is a decision you make together with your provider.

How do I know when labour has started and when to go in?

The Society of Obstetricians and Gynaecologists of Canada (SOGC) lists early signs including the baby "dropping," a "brownish or bloody discharge" as the mucus plug releases, and irregular contractions that become regular. SOGC says that "once your contractions are happening every 5 minutes or less, it is usually an indication that labour is beginning," with "at least 10 contractions in an hour" as a convenient guide. Expect the first part to be slow — SOGC calls the latent phase "the longest stage of labour," and says that in a healthy term pregnancy "you will typically be at home through this phase," with admission usually coming "once your cervix has dilated to 4 cm." If your water breaks at term, SOGC notes your provider "may offer or recommend induction of labour" — so call them, and if you are unsure whether it has broken, bring the pad you were wearing so the fluid can be tested.

Week 39 Baby calendar

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Sources & References

Mayo Clinic — Fetal development: The 3rd trimester (Week 39, Week 40)
Society of Obstetricians and Gynaecologists of Canada (SOGC) — Overdue pregnancy
Society of Obstetricians and Gynaecologists of Canada (SOGC) — Labour 101
Society of Obstetricians and Gynaecologists of Canada (SOGC) — Gestational hypertension and preeclampsia
Society of Obstetricians and Gynaecologists of Canada (SOGC) — Fetal movement and kick counts
Society of Obstetricians and Gynaecologists of Canada (SOGC) — Symptoms of pregnancy
Public Health Agency of Canada — Folic acid, healthy pregnancy and neural tube defect prevention
Health Canada — Caffeine in Foods (recommended maximum daily intake)

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