At 39 weeks pregnant you are about 9 months along and officially full term, with about 1 week to go until your estimated due date.
At 39 weeks pregnant your baby is full term and adding the last layers of warming fat, you are likely seeing your provider every week. Mayo Clinic notes that many people give birth before or after their due date.
This guide covers development, size, symptoms, signs of labor, what the evidence says about induction at 39 weeks, sleep and when to call. Every clinical detail was read in October 2026 on the primary sources named in the text.
Key Takeaways
39 weeks pregnant is about 9 months, or 37 weeks after conception (Mayo Clinic), with about 1 week to go.
Full term runs from 39 weeks 0 days through 40 weeks 6 days (ACOG and SMFM, via NICHD).
Mayo Clinic gives about 6 1/2 pounds at week 38 and about 7 1/2 pounds at week 40; sizes vary.
ACOG says offering elective induction at 39 weeks to low-risk first-time mothers is reasonable after shared decision-making.
Call right away if your water breaks, you bleed, contractions become regular or your baby moves less.
Table of Contents
39 Weeks Pregnant at a Glance
Quick Answer
At 39 weeks pregnant you are about 9 months along, near the end of your 9th month, with about 1 week to go until your estimated due date. You are in the third trimester and your baby is now full term (39 weeks 0 days through 40 weeks 6 days, per the ACOG and SMFM definitions reported by NICHD).
39 weeks pregnant
What to know
Trimester
Third. ACOG, as reported by UPMC, starts it at the beginning of the 29th week and it lasts until delivery.
Month
About 9 months (the end of your 9th month), counting 4 weeks and a few days per month. Months are a convention, not a medical unit.
Weeks to go
About 1 (40 minus 39, counted from the first day of your last menstrual period).
Term status
Full term, from 39 weeks 0 days (ACOG and SMFM, via NICHD; Mayo Clinic).
Baby’s size
No week 39 figure in our sources: about 6 1/2 pounds at week 38 and about 7 1/2 pounds at week 40 (Mayo Clinic). Size varies a lot.
Common symptoms
Stronger Braxton Hicks contractions, pelvic pressure, frequent urination, back and hip pain, trouble sleeping.
This week’s care focus
Weekly visits, signs of labor, your baby’s movements and your induction questions.
39 weeks pregnant: quick facts with sources.
How the weeks are counted. Mayo Clinic explains that your provider sets your due date by counting ahead 40 weeks from the start of your last period. That is why Mayo Clinic describes week 39 as 37 weeks after conception. If an early ultrasound changed your due date, go by your adjusted dates.
Term label
Gestational age
Early term
37 weeks 0 days through 38 weeks 6 days
Full term (you are here)
39 weeks 0 days through 40 weeks 6 days
Late term
41 weeks 0 days through 41 weeks 6 days
Postterm
42 weeks 0 days and beyond
ACOG and SMFM term definitions, as reported by NICHD (read October 2026).
What full term means for your baby. NICHD says key developmental processes happen between 37 and 39 weeks, and that babies born at or after 39 weeks have better health outcomes than babies born before 39 weeks. Unless there is a health problem, it says, reaching full term means 39 weeks, not 37.
Your Baby’s Development at 39 Weeks
Source and timing
What it says is happening
Mayo Clinic, week 38
The measurements around the head and around the belly are about the same. The toenails have reached the tips of the toes, and most of the lanugo (fine body hair) is gone.
Mayo Clinic, week 39 (37 weeks after conception)
The baby is considered full term. The chest is getting larger, and fat is being added all over the body to keep your baby warm after birth.
Nemours KidsHealth, week 39
Most of the vernix (the waxy coating on the skin) has disappeared, as has the lanugo.
Nemours KidsHealth, week 39
Your body has been passing antibodies to the baby through the placenta that will help your baby’s immune system fight infection for the first 6 to 12 months of life.
Fetal development around week 39, by source.
Head down? Mayo Clinic says most babies have turned head down by about week 36. If yours is still bottom or feet first, ask what the plan is; our breech baby guide explains the options.
How Big Is Your Baby at 39 Weeks?
Our primary sources give no week 39 measurement, so here are Mayo Clinic’s figures on either side.
Source
Week
Length
Weight
Mayo Clinic
38
Not given
About 6 1/2 pounds (2,900 g); some nearly 9 pounds (4,000 g) or more
Mayo Clinic
40
Around 14 inches (360 mm), crown to rump
About 7 1/2 pounds (3,400 g)
Baby size near 39 weeks, by source (read October 2026).
Crown to rump runs from the top of the head to the bottom of the tailbone (Mayo Clinic), so a newborn’s head-to-heel length is longer. Mayo Clinic stresses that healthy babies come in lots of sizes.
A 39 week ultrasound? MedlinePlus says there are no routine ultrasounds for every pregnant woman in the third trimester, and that extra testing may be needed for some, including those pregnant for more than 40 weeks.
39 Weeks Pregnant Symptoms
Braxton Hicks contractions: Nemours KidsHealth says they may become more pronounced at 39 weeks and can be as strong as true labor, but they do not become regular or more frequent.
Lightening: Mayo Clinic describes the baby’s head settling deep into the pelvis, from a few weeks to a few hours before labor.
Frequent urination, back, hip and nerve pain, heartburn, hemorrhoids, leaking breasts, nesting: all on UPMC’s third trimester list.
Swelling: of the face, ankles, feet and hands (UPMC). Sudden or severe swelling of the hands or face needs care right away.
Signs labor may be close. Mayo Clinic describes these changes in the run-up to labor:
Mucus plug: it can loosen, causing clear, pink or slightly bloody discharge; bleeding as heavy as a period needs prompt care. More on the mucus plug.
Cervical changes: as early labor begins the cervix softens, shortens and thins (effacement), then opens (dilation).
Water breaking: a trickle or a gush. Contact your care team even if you are not sure it is amniotic fluid. Nemours KidsHealth says it often does not break until well into labor.
Contractions that build: see the table below.
Braxton Hicks (false labor)
True labor
Pattern
No clear pattern
Usually 2 to 5 minutes apart as labor progresses
Length
Varies
About 60 to 90 seconds
Movement or rest
May stop when you walk, rest or change position
Keep going no matter what you do
Strength
Typically weak
Grow stronger over time
False labor vs true labor, as described by Mayo Clinic (read October 2026).
Your belly may look lower if your baby has dropped into your pelvis, and you may feel heavy, achy and very ready.
Your baby’s movements: MedlinePlus says movement changes as the due date nears: active and quiet periods, mostly rolling and squirming, with an occasional strong kick. If movement seems to drop, eat a snack and lie down for a few minutes, and call your provider if you still feel little movement. Do not wait for your next visit.
Your due date: Mayo Clinic says it is simply an estimate of when you will be 40 weeks along, not a prediction of when your baby will arrive.
Your emotions: the waiting can feel long. The CDC lists thoughts of harming yourself or your baby as an urgent warning sign: get care right away.
Prenatal Care, Tests and Appointments Around Week 39
What
Timing
Source
Prenatal visits
Every week after week 36
MedlinePlus
Pelvic exam to see whether the cervix is dilating
May be done
MedlinePlus
Group B strep test
A few weeks before your due date (usually already done)
MedlinePlus
Late pregnancy visits, as read in October 2026.
Cervical checks. Mayo Clinic says dilation is measured from 0 to 10 centimeters and active labor begins at around 6. One check is a snapshot, not a countdown.
Induction at 39 weeks: what the evidence says. You may hear about elective induction (inducing labor without a medical reason) at 39 weeks. It is a choice to talk through with your provider, not a rule either way.
The ARRIVE trial: ACOG’s practice advisory describes this trial, in which 6,106 low-risk first-time mothers were randomly assigned to induction at 39 weeks or to waiting for labor (expectant management). Cesarean births were less common with induction (18.6% vs 22.2%), as were gestational hypertension and preeclampsia (9.1% vs 14.1%), with no statistical difference in the main combined measure of perinatal death and serious complications.
ACOG’s position: the advisory (reaffirmed October 2022) says it is reasonable to offer elective induction to low-risk first-time mothers at 39 weeks after shared decision-making, and that it may depend on your preferences and the hospital’s resources. It also says a birth before 39 weeks 0 days without a medical reason is not appropriate. Ask how the findings apply to you.
Questions to bring: Would you offer me an induction? What if I prefer to wait? What if my water breaks before contractions? Mayo Clinic notes that once the water breaks, the longer labor takes to start, the higher the infection risk, and induction may be recommended.
What to Do This Week: A Simple Checklist
Keep your hospital bag by the door (UPMC) and your provider’s after-hours number and the labor and delivery address in your phone.
Check the car seat is installed (UPMC), following the seat and vehicle manuals.
Confirm your pediatrician. UPMC says the first visit should be two to three days after you get home.
Talk through your induction and waiting preferences with your provider and your support person.
Set up your baby’s sleep space and skim our 4th trimester guide.
Sleep at 39 Weeks Pregnant
Difficulty sleeping is on UPMC’s third trimester list: a big belly, bathroom trips, heartburn and practice contractions all compete with rest.
Sleep position. UPMC says to avoid sleeping on your back as your belly grows, because the weight of your uterus can compress a nearby blood vessel, which may make you dizzy and reduce blood flow to your baby. If you roll onto your back, the discomfort usually wakes you so you can shift (UPMC).
Contact your care team right away if any of these happen, or for any other reason if you are unsure what to do:
Your water breaks, even if you are not sure it is amniotic fluid (Mayo Clinic).
Regular, painful contractions, or your baby moves less (MedlinePlus).
Any bleeding, or discharge with an odor (MedlinePlus).
Fever, chills, pain when you urinate, headaches, vision changes or significant swelling (MedlinePlus).
Urgent maternal warning signs. The CDC says to seek medical care immediately for any of these:
A headache that will not go away or gets worse over time, or changes in your vision.
Dizziness or fainting, or a fever of 100.4 F or higher.
Extreme swelling of your hands or face.
Trouble breathing, chest pain or a fast-beating heart.
Severe nausea and throwing up, or severe belly pain that does not go away.
Your baby’s movement stopping or slowing.
Vaginal bleeding or fluid leaking.
Severe swelling, redness or pain of your leg or arm, or overwhelming tiredness.
Thoughts about 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 in 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 39 weeks pregnant considered full term?
Yes. Under the ACOG and SMFM definitions reported by NICHD, full term runs from 39 weeks 0 days through 40 weeks 6 days, and Mayo Clinic agrees. NICHD says babies born at or after 39 weeks have better health outcomes than babies born before 39 weeks.
How many months is 39 weeks pregnant?
About 9 months, near the end of your 9th month, counting 4 weeks and a few days per month. You have about 1 week to go until your estimated due date. Months are only a convention, so your provider keeps counting in weeks.
How big is a baby at 39 weeks?
Our primary sources give no week 39 figure. Mayo Clinic says about 6 1/2 pounds at week 38, with some babies nearly 9 pounds or more, and about 7 1/2 pounds with a crown-to-rump length of around 14 inches at week 40. Sizes vary.
Can I ask to be induced at 39 weeks?
You can ask. ACOG says it is reasonable for obstetricians and hospitals to offer elective induction at 39 weeks to low-risk women having their first baby, after a shared decision-making discussion, and that it may depend on your preferences and hospital resources. Talk with your provider about how this applies to you.
Is it normal to have no signs of labor at 39 weeks?
Yes, it can be. Mayo Clinic says the due date is only an estimate, many people give birth before or after it, and you should not worry if it passes without labor starting. Keep your weekly visits, watch your baby’s movements, and call if anything changes or worries you.
How do I know if I am losing my mucus plug or my water broke?
Mayo Clinic says a loosening mucus plug causes clear, pink or slightly bloody discharge, while water breaking can be a trickle or a gush of fluid. If you think your water broke, contact your care team even if you are not sure. Bleeding as heavy as a period needs prompt attention.
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