At 40 weeks pregnant you have reached your estimated due date: you are about 9 months and a week along, still full term, and your baby might weigh about 7 1/2 pounds.
At 40 weeks pregnant your baby is ready and you are probably more than ready, yet most babies do not arrive on the due date. UPMC reports, citing ACOG, that only 5% of births occur on the due date, and Mayo Clinic calls the due date an estimate, not a prediction.
This guide covers your baby’s size, the signs of labor, what your provider may do if you go past 40 weeks (monitoring, membrane sweeping and induction), sleep and when to call. Every clinical detail was read in October 2026 on the primary sources named in the text.
Key Takeaways
40 weeks pregnant is your estimated due date: about 9 months and a week, or 38 weeks after conception (Mayo Clinic).
Full term runs through 40 weeks 6 days, late term is 41 weeks, and postterm is 42 weeks and beyond (NICHD).
Mayo Clinic says a baby at 40 weeks might measure about 14 inches crown to rump and weigh about 7 1/2 pounds.
MedlinePlus says providers typically order a nonstress test and biophysical profile at 41 weeks and often recommend induction between 41 and 42 weeks.
Call right away if your water breaks, you bleed heavily, your baby moves less or contractions become regular and strong.
Table of Contents
40 Weeks Pregnant at a Glance
Quick Answer
At 40 weeks pregnant you have reached your estimated due date. You are about 9 months and a week along, in the third trimester, and still full term until 40 weeks 6 days (NICHD). Mayo Clinic says your baby might weigh about 7 1/2 pounds. Going past the due date is common, and your provider will talk with you about monitoring and options.
40 weeks pregnant
What to know
Trimester
Third. ACOG, as reported by UPMC, starts it at 28 weeks 0 days and says it lasts until delivery.
Month
About 9 months and a week, counting 4 weeks and a few days per month (strict 4 week blocks would make it 10). Months are a convention, not a medical unit.
Weeks to go
Zero (40 minus 40, counted from the first day of your last menstrual period). This is your estimated due date.
Term status
Full term through 40 weeks 6 days; late term from 41 weeks 0 days; postterm from 42 weeks (NICHD, reporting ACOG and SMFM).
Baby’s size
About 14 inches (360 mm) crown to rump and about 7 1/2 pounds (3,400 g), according to Mayo Clinic.
Common symptoms
Pelvic pressure, frequent urination, Braxton Hicks contractions, back and hip pain, trouble sleeping.
This week’s care focus
Signs of labor, your baby’s movements, and a plan with your provider in case labor does not start soon.
40 weeks pregnant: quick facts with sources.
How the weeks are counted. Mayo Clinic says your provider sets your due date by counting ahead 40 weeks from the start of your last period, so the first week or two of that count is not actually pregnancy. That is why Mayo Clinic describes week 40 as 38 weeks after conception. MedlinePlus adds that due dates come from your last period, the size of your uterus early on and early ultrasound, and that each method has limits. If an early ultrasound changed your due date, go by your adjusted dates.
Your Baby’s Development at 40 Weeks
Source and timing
What it says
NICHD, weeks 37 to 39
The lungs, liver and brain go through significant development between 37 and 39 weeks.
Mayo Clinic, week 38
Head and belly measurements are about the same, the toenails reach the toe tips, and most of the lanugo (fine body hair) is gone.
Mayo Clinic, week 39
Full term. The chest is getting larger, and fat is being added all over to help keep your baby warm after birth.
Mayo Clinic, week 40
About 14 inches crown to rump and about 7 1/2 pounds. No new milestones are listed.
Fetal development near 40 weeks, by source.
NICHD says that for a healthy pregnancy, outcomes for both baby and mother are best if the baby stays in the womb for at least 39 weeks. At 40 weeks you are past that point, so your baby is ready whenever labor starts or your care team decides it is time.
If pregnancy goes on. Mayo Clinic describes postmaturity syndrome in some babies born well past the due date: less fat under the skin, less vernix (the creamy coating), less lanugo and meconium staining. It is linked to postterm pregnancy, not to reaching your due date, and it is one reason your provider checks on your baby more closely from here.
How Big Is Your Baby at 40 Weeks?
Week
Length
Weight
Source
38
Not given
About 6 1/2 pounds (2,900 g)
Mayo Clinic
40
About 14 inches (360 mm), crown to rump
About 7 1/2 pounds (3,400 g)
Mayo Clinic
Baby size near 40 weeks, as read in October 2026.
Crown to rump means the top of the head to the bottom, with the legs left out, so your baby’s head-to-heel length at birth will be noticeably longer. Mayo Clinic stresses that healthy babies come in lots of sizes. It also says a pregnancy that goes past its due date carries a higher chance of a larger than average baby (fetal macrosomia), which can raise the chance of an assisted delivery, a C-section or shoulder dystocia.
A 40 week ultrasound? Not every pregnancy has one. MedlinePlus says that before 41 weeks providers usually take no action unless problems arise, and that at 41 weeks they typically order a nonstress test and a biophysical profile, which includes an ultrasound. Your provider may order a scan sooner if there is a concern.
40 Weeks Pregnant Symptoms
UPMC’s third trimester list still applies. You may have many of these or very few:
Lightening: Mayo Clinic says the baby’s head moves lower into your pelvis, which can make your belly feel different, from weeks to hours before labor.
Pelvic pressure, frequent urination, back and hip pain, sciatica, heartburn: all on UPMC’s list.
Braxton Hicks contractions: Mayo Clinic says they come and go without a pattern and may stop when you walk, rest or change position.
Swelling: of the face, ankles, feet and hands is common (UPMC), but UPMC says to seek care right away for sudden or severe swelling of the hands or face.
Signs that labor may be starting, as Mayo Clinic describes them:
Mucus plug: late in pregnancy it can move, causing clear, pink or slightly bloody discharge, sometimes days before labor. See our mucus plug guide.
Cervical changes: the cervix softens, shortens and thins (effacement), then opens.
Water breaking: a trickle or a gush. Contact your care team and go in, even if you are not sure it is amniotic fluid.
Contractions: true labor contractions are typically 2 to 5 minutes apart and last about 60 to 90 seconds.
Question
Braxton Hicks (false labor)
True labor
Pattern
No clear pattern
Closer together over time
Length
Varies
About 60 to 90 seconds
Activity or rest
May stop
Continue no matter what you do
Strength
Usually weak, or strong then fading
Stronger, until talking is hard
False vs true labor, as described by Mayo Clinic (October 2026).
Your belly may sit lower if the baby has dropped, and for many people the waiting is harder than any physical symptom.
Your cervix: Mayo Clinic says the cervix is typically 3.5 to 4 centimeters long before labor, and dilation is measured from 0 to 10 centimeters, with active labor at about 6 centimeters or more. One check is a snapshot, not a countdown.
Your baby’s movements: your baby has less room, but movement should not stop. The CDC lists a baby moving less or not at all as an urgent warning sign that needs medical care right away. Do not wait for your next appointment.
Why some pregnancies go past the due date. Mayo Clinic lists a first pregnancy, a previous pregnancy that went two weeks past its due date, carrying a boy, a body mass index of 30 or higher, and a due date calculated incorrectly (for example, from an ultrasound done after 22 weeks). MedlinePlus says that when a pregnancy truly goes past 42 weeks, the cause is unknown.
Prenatal Care, Tests and Appointments Around Week 40
What happens now depends on your health, your baby’s health and your provider. Here is what the primary sources describe:
Timing
What your provider may do
Source
Before 41 weeks
Usually no action unless problems arise
MedlinePlus
More than a week past the due date
A nonstress test, which measures your baby’s heart rate
Mayo Clinic
At 41 weeks
A nonstress test and a biophysical profile (an ultrasound that checks activity and fluid)
MedlinePlus
One to two weeks past the due date
Induction may be considered if labor has not started
Mayo Clinic
Between 41 and 42 weeks
Risks rise, and providers often recommend induction
MedlinePlus
Monitoring after the due date, as read in October 2026.
Mayo Clinic says a biophysical profile checks your baby’s heart rate, breathing, muscle tone and movement, usually with an amniotic fluid check. MedlinePlus says normal results may mean waiting for labor to start on its own, and abnormal results may lead to a decision to induce.
Induction options a provider may discuss (Mayo Clinic):
Method
What it is
Cervical ripening
Medication, or a catheter with an inflatable balloon, to soften and open the cervix.
Membrane sweeping
A gloved finger separates the amniotic sac from the cervix and lower uterus.
Rupturing the membranes
A thin plastic hook opens the amniotic sac if it is still intact.
Oxytocin (Pitocin)
A hormone medication that starts contractions.
Ripening, rupturing and oxytocin are typically done in a hospital labor and delivery unit (Mayo Clinic).
Benefits and risks. Mayo Clinic says a person with a low-risk pregnancy may choose induction at 39 to 40 weeks, a timing linked to lower risks of stillbirth, a larger than average baby and pregnancy-related high blood pressure. It also lists risks: an induction that does not work after 24 or more hours may end in a C-section; very strong or irregular contractions can lower the baby’s heart rate; some methods raise infection risk; uterine rupture is rare but serious; and the uterus may not contract as it should after birth, which can cause bleeding.
Waiting with monitoring and planning an induction are both choices a provider may offer. Ask what your results show, what your provider recommends for you and why, which method they would use, and what to do if your water breaks before contractions.
What to Do This Week: A Simple Checklist
Keep your hospital bag by the door (UPMC) and your provider’s after-hours number in your phone.
Check that the car seat is installed (UPMC), following the seat and vehicle manuals.
Confirm your pediatrician. UPMC says the first baby visit should be two to three days after you come home.
Notice your baby’s usual movement each day, and call right away if it slows or stops (CDC).
Write down your provider’s plan for after your due date: test dates, any induction date and when to call.
Arrange childcare for older children for when labor starts (UPMC).
Skim our 4th trimester guide so recovery, feeding and newborn sleep are not brand new in week one.
About do-it-yourself labor tricks. Mayo Clinic says there is no evidence that anything you do will start labor, that exercise and sex do not induce labor, and that you should not use herbal supplements because they can harm the baby. Check with your provider before trying anything to bring on labor.
Sleep at 40 Weeks Pregnant
Trouble sleeping is on UPMC’s third trimester list, and at 40 weeks bathroom trips, heartburn and a mind that keeps checking for contractions all compete with rest.
Sleep position. UPMC says that as your belly grows you should avoid sleeping on your back, because the weight of your uterus can compress a blood vessel that supplies blood to your uterus, which may make you dizzy and reduce blood flow to your baby. If you roll onto your back at night, UPMC says discomfort will usually wake you so you can change position.
Learn the call list below and the false vs true labor table above.
Keep the car fueled or charged and the route planned, day and night.
Go to monitoring appointments if you can and write down the plan.
Field the “Any baby yet?” messages and take on night chores so she can rest.
If she mentions thoughts of harming herself or the baby, the CDC says to seek medical care immediately.
Looking Ahead: What Comes Next
40 weeks 6 days: the last day of full term (NICHD).
41 weeks 0 days to 41 weeks 6 days: late term (NICHD, Mayo Clinic). Expect testing such as a nonstress test and biophysical profile (MedlinePlus).
42 weeks and beyond: postterm (NICHD, Mayo Clinic). MedlinePlus words it slightly differently, calling a pregnancy that lasts more than 42 weeks post-term.
Why providers watch closely. MedlinePlus says the placenta may work less well after the due date, which can reduce the oxygen and nutrients your baby receives, and that low amniotic fluid can press on the umbilical cord. It says stillbirth is not common but begins to increase the most after 42 weeks. Mayo Clinic adds risks for the mother in a postterm pregnancy: severe vaginal tears, infection and bleeding after birth. These risks are the reason for the extra checks.
Your water breaks, even if you are not sure it is amniotic fluid; Mayo Clinic says to go to your hospital or birthing center.
You have vaginal bleeding as heavy as a typical period (Mayo Clinic).
Contractions are getting closer together and stronger and keep going whatever you do (Mayo Clinic), or you meet your provider’s own timing rule.
You are not sure whether you are in labor (Mayo Clinic).
Urgent maternal warning signs. The CDC says to seek medical care immediately for any of these:
A headache that will not go away, gets worse, or is severe and sudden; dizziness, fainting or gaps in memory.
Vision changes such as flashes of light, blind spots, blurriness or double vision.
A fever of 100.4 F (38 C) or higher, or marked swelling of your face or hands.
Trouble breathing, chest pain or pressure, or a racing or irregular heartbeat.
Severe belly pain that does not go away, or severe nausea and vomiting.
Your baby moving less or not at all; bleeding heavier than spotting, leaking fluid or foul-smelling discharge.
Severe swelling, redness, warmth or pain in a leg or arm; sudden, overwhelming exhaustion; or thoughts of harming yourself or your baby.
The CDC says to tell whoever you speak to that you are pregnant. If you cannot reach your provider quickly, go to labor and delivery or the nearest emergency room, and call 911 for an emergency such as severe chest pain, severe trouble breathing, a seizure or heavy bleeding. This article is general education, not medical advice.
Frequently Asked Questions
Is it normal to be 40 weeks pregnant with no signs of labor?
Yes, it is common. UPMC reports, citing ACOG, that only 5% of births occur on the due date and that babies are typically born between 39 and 41 weeks. Mayo Clinic calls the due date an estimate. Keep your appointments, watch your baby’s movements and ask your provider about the plan if labor does not start.
How many months is 40 weeks pregnant?
About 9 months and a week if you count 4 weeks and a few days per month, which is why many people say pregnancy lasts 9 months. If you count strict 4 week blocks, 40 weeks is exactly 10. Months are only a convention, so your provider counts in weeks.
How big is a baby at 40 weeks?
Mayo Clinic says a baby at 40 weeks might measure about 14 inches (360 millimeters) from crown to rump, which leaves out the legs, and weigh about 7 1/2 pounds (3,400 grams). Healthy babies come in many sizes, so yours may be larger or smaller than this average.
What happens if I go past my due date?
MedlinePlus says providers usually take no action before 41 weeks unless problems arise. Around 41 weeks they typically order a nonstress test and a biophysical profile. Normal results may mean waiting, while abnormal results may lead to induction. Risks rise between 41 and 42 weeks, when providers often recommend induction.
What is a membrane sweep?
Mayo Clinic describes membrane sweeping as a method in which a gloved finger separates the amniotic sac from the cervix and lower uterus. It is one of several induction methods your provider may discuss, along with cervical ripening, breaking the water and oxytocin. Ask whether it suits your situation and what to expect afterward.
Can I do anything to start labor naturally?
Mayo Clinic says there is no evidence that anything you do will start labor, that exercise and sex do not induce labor, and that you should not use herbal supplements because they can harm the baby. Talk with your provider before trying any method, and ask about medical options if you pass your due date.
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