You've reached full term. At 39 weeks, your baby is ready — and so are you. The question now isn't if, but when.

At 39 weeks, you have officially reached what ACOG (the American College of Obstetricians and Gynecologists) calls full term — defined as 39 weeks 0 days through 40 weeks 6 days. This is the distinction that matters: babies born during this window have the best outcomes for lung function, brain development, and feeding. The weeks leading up to 39 0/7 matter, which is why ACOG and SMFM advise against non-medically-indicated delivery before this point.

This article draws on guidance from NHS [1] [2] [3], WHO Antenatal Care (2016) [4], and the Royal Thai College of Obstetricians and Gynaecologists (RTCOG) [5].

Your baby at week 39

Your baby is approximately 50.7 cm long (head to heel) — about the size of a watermelon — and weighs around 3.3 kg on average, though healthy babies vary considerably [1].

What's happening this week:

Skin — a protective layer of vernix caseosa (the white, waxy coating) still covers parts of the body and helps ease passage through the birth canal
Lungs — surfactant production is complete; the lungs are ready to take their first breath of air
Brain and nervous system — still developing rapidly; the brain at birth is only one-quarter of its adult size, but all the circuitry for breathing and feeding is in place
Fat reserves — subcutaneous fat is fully laid down, giving your baby the rounded cheeks and limbs of a full-term newborn
Position — most babies are head-down (cephalic), engaged in the pelvis and ready for birth

What you may be feeling

As your body prepares for labor, you may notice:

Pelvic pressure and heaviness — as the baby descends deeper into the pelvis (lightening/ engagement). Breathing may feel easier but the urge to urinate more frequent
Increased vaginal discharge — thin, white discharge is normal; a slimy, jelly-like blob that may be pink- or blood-tinged is a bloody show (mucus plug), a sign that your cervix is beginning to change [1]
Back pain — as the baby's weight shifts further downward
Nesting instinct — a sudden burst of energy to organize or clean; completely normal
Braxton-Hicks contractions — irregular practice contractions that don't follow a pattern; they're doing the preparatory work on your cervix
Disrupted sleep — harder to get comfortable; your body is readying itself

Weight gain typically slows or stops at this stage. Total gain throughout pregnancy varies by starting BMI but is usually 11–16 kg for a normal-weight pregnancy.

Recognizing labor signs [2]

Knowing the difference between false and true labor will help you time your trip to the hospital or birth center.

True labor contractions

True contractions:

Become progressively stronger, longer, and closer together
Do not ease when you change position or rest
Often start in the lower back and radiate forward
Follow a regular pattern

The 5-1-1 rule

Contact your care team when contractions are:

Every 5 minutes apart
Lasting at least 1 minute each
Sustained for 1 hour

At this point, it's time to head to the hospital. Call sooner if this is your first pregnancy, if your waters break, or if anything feels urgent.

Waters breaking

When the amniotic sac ruptures, you may feel a sudden gush or a slow trickle of fluid you cannot control. The fluid is typically clear and odorless. Note the time it starts, the color, and any odor, and contact your care team immediately — if labor doesn't start on its own within 24 hours, induction is usually recommended to reduce infection risk [3].

Bloody show

A pink or blood-streaked mucus discharge means the cervical mucus plug has come away. Labor may follow within hours or a few days — or not at all for another week. Bloody show alone is not a reason to rush to the hospital unless accompanied by other signs.

Induction of labor: what to know

Some labors don't start on their own. Your doctor may discuss induction of labor — medically starting contractions artificially — if:

Your pregnancy goes past 41 weeks (overdue)
Your waters break but contractions don't start within 24 hours
You have a medical condition such as hypertension, gestational diabetes, or reduced fetal movement
The placenta is not functioning well

There is also evidence from a large clinical trial (the ARRIVE trial, published in the New England Journal of Medicine, 2018) that elective induction at 39 weeks for low-risk first-time mothers did not increase c-section rates and may be associated with slightly lower rates — but this is a nuanced finding that applies only to specific clinical situations. Whether induction is right for you at 39 weeks is a conversation to have with your OB, not a default recommendation.

Methods your care team may use [3]

Membrane sweep (stretch and sweep) — your doctor or midwife sweeps a finger around the inside of your cervix to separate the amniotic membranes from the cervix, releasing hormones that may trigger labor naturally. This is often tried first.
Cervical ripening — hormones (prostaglandins) delivered as a vaginal gel, pessary, or tablet to soften and open the cervix
Oxytocin drip — a synthetic hormone given through an IV to stimulate regular contractions once the cervix is ready
Artificial rupture of membranes (ARM / amniotomy) — your membranes are broken intentionally to start or speed up labor

Induced labor is typically more intense than labor that starts spontaneously, and you are more likely to need pain relief. Occasionally induction doesn't succeed and a c-section becomes necessary.

Keeping track of fetal movement

Your baby should still be moving regularly right up to — and during — labor. A change in how your baby moves can be an early warning sign that the placenta is not delivering enough oxygen.

Count fetal kicks every day — most women notice their baby has a recognizable pattern. If you notice decreased fetal movement (fewer movements than usual, or no movement for several hours), do not wait: contact your care team or go to your hospital the same day [1].

When to go to the hospital right away

Go immediately — do not wait to "see how things develop":

Regular contractions following the 5-1-1 pattern [2]
Waters breaking — any gush or uncontrollable trickle
Vaginal bleeding more than the light spotting of a bloody show
Decreased fetal movement — less movement than usual, or no movement for hours
Severe headache, blurred vision, pain under the ribs, or sudden swelling of face or hands — possible signs of pre-eclampsia requiring emergency care
Fever above 38°C or chills
Any pain or symptom that feels wrong — trust your instincts

The labor ward team has taken hundreds of these calls. No call at 2 a.m. is too small when you are this close.

Preparing for the final stretch

If you haven't yet:

Hospital bag should be packed and by the door. Include ID, insurance card, antenatal notes, your birth preferences, phone charger, and items for your support person.
Car seat installed. Many hospitals won't discharge a newborn without one confirmed in the car.
Birth preferences reviewed with your care team. Labor analgesia options, your support person's role, cord-clamping preferences.
Arrange support. Who will come with you? Who will be reached first after the birth?

Summary

Week 39 is full term — your baby is physiologically ready, and your body is preparing for the work ahead.

Key principles for this week:

Know your labor signs — 5-1-1 rule for contractions, waters breaking, and bloody show
Count fetal kicks daily — decreased movement means same-day contact with your care team
Hospital bag packed, car seat fitted — you could leave tonight
Discuss induction with your OB if it hasn't happened already — know the plan
Call without hesitation — bleeding, vision changes, severe headache, no movement, high fever are all "go now" signals

Every labor is different. Some start gradually over hours; others move fast. Being familiar with the signs — and having your care team's number saved — is the best preparation you can make this week.

Pregnancy Week 39: Full Term — What to Expect Before Labor Begins