Pregnancy Week 37: Baby Now Full Term

Week 37 is the "any minute now" zone. Baby weighs almost 3 kilograms, has practiced breathing thousands of times, is in position, and could technically arrive any day. Officially you're still 3 weeks from your due date, and most babies wait until closer to it — but you're firmly inside the safe zone for delivery.

This guide walks through what's happening at 37 weeks pregnant, how to spot real labor and the mucus plug and bloody show, the difference between "early term" and "full term," what to keep in your hospital bag, and exactly when to call.

This article is educational, not medical advice. Pregnancy is deeply individual, and your obstetrician or midwife is the person who knows your history. We're the team behind Vyve, the private AI pregnancy and cycle tracker, and Vyve is a tracking tool — not a diagnostic one.

What's happening this week

You're 3 weeks from your due date. Appointments are typically weekly now, with cervical checks in many practices to see if things are starting to progress. Baby is fully developed and just gaining a bit more fat and weight. Most of what happens from here is waiting.

If you want to see what's ahead, check week 38 and week 40 — the due date.

Baby's size and development at week 37

At 37 weeks pregnant, your baby is about the size of a winter melon or a small watermelon — roughly 48 centimeters (18.9 inches) from head to heel, weighing around 2.9 kilograms (6.4 pounds).

Here's what's happening this week:

• Lungs are ready. Fully mature and producing enough surfactant.
• Practice breathing continues. Baby's chest rises and falls.
• Baby is head-down for the vast majority.
• Brain and nervous system continue developing rapidly. This continues well past birth.
• Meconium (baby's first stool) is building in the intestines.
• Fingernails and toenails are fully grown and may need trimming after birth.
• Fat continues accumulating. Baby's skin is smooth and pink.
• Weight gain slows a bit. But not by much — baby's still adding grams every day.

Early term vs full term

Definitions matter here:

• Early term: 37 weeks 0 days through 38 weeks 6 days.
• Full term: 39 weeks 0 days through 40 weeks 6 days.
• Late term: 41 weeks 0 days through 41 weeks 6 days.
• Post-term: 42 weeks 0 days and beyond.

Babies born at 37 weeks do very well, but the "early term" label matters for one specific reason: elective inductions or scheduled C-sections without a medical reason are typically not done before 39 weeks. Every extra week gives baby's brain and lungs a little more finishing time. If labor starts naturally at 37, though, it's welcomed.

Your symptoms and body changes

Common experiences:

• Lightening (baby dropping). Baby moves lower into the pelvis; breathing easier, more pelvic pressure.
• Braxton Hicks more frequent. Some feel like the real thing.
• Bloody show or mucus plug loss. May happen this week or over the coming weeks.
• Frequent bathroom trips. Baby is right on the bladder.
• Lower back pain and pelvic pressure.
• Trouble sleeping. Bump, bathroom, nerves.
• Nesting. Real for many.
• Emotional intensity. Anticipation, anxiety, impatience — all normal.
• Increased discharge. Body prepping for birth.
• Colostrum may leak more.

Real labor vs Braxton Hicks

Common rule: 5-1-1 for first-time labor — contractions 5 minutes apart, each 1 minute, for at least 1 hour. Second and later births often use 4-1-1 or similar. Your clinician will have given you specific guidance; use theirs.

Mucus plug and bloody show

The mucus plug is a thick collection of mucus that seals the cervix during pregnancy. As your cervix starts to soften and open (dilate and efface) in preparation for labor, the plug can dislodge. You may notice:

• A blob or streak of thick mucus (clear, pink, or brownish)
• Small amounts over several days rather than one big loss
• Sometimes tinged with blood (that's the "bloody show")

Losing the plug is a sign that things are progressing, but labor could still be hours, days, or even weeks away. It's not on its own a reason to head to the hospital. If bleeding is heavier than light spotting, call.

Hospital bag reminders

Your bag should be packed and near the door by now. Double-check:

For you: ID, insurance, birth plan, loose clothes, robe, non-slip socks, nursing bras, heavy-flow pads, toiletries, phone charger with long cable, pillow from home, snacks and drinks (for after), comfort items.

For baby: Going-home outfit (season-appropriate), hat, socks, swaddle blanket, diapers, wipes, installed car seat.

For partner: Change of clothes, toiletries, snacks, phone charger, pillow if staying overnight, camera.

In the car / by the door: Bag itself, car seat installed, hospital route in your maps app.

On your phone: Clinician's number, hospital labor and delivery number, birth plan, insurance details, emergency contacts, playlist.

When to call your doctor

Call your clinician (or go to the hospital) if you have:

• Regular painful contractions per your team's rule (usually 5-1-1)
• Waters breaking — gush or persistent leak (call even if no contractions)
• Any vaginal bleeding — more than a small streak with mucus plug
• Decreased fetal movement — noticeable drop from normal pattern
• Severe headache with vision changes or upper abdominal pain (possible preeclampsia)
• Sudden severe swelling
• Fever above 38°C / 100.4°F
• Severe or one-sided abdominal pain
• Fainting or persistent dizziness
• Anything else that feels seriously off — trust your instincts

What to ask your doctor

• What's my Group B strep status?
• Where is baby's head — engaged, still floating?
• Am I dilated/effaced at all? (If you want to know)
• What's the plan if I go past 40 or 41 weeks?
• Any signs of preeclampsia I should watch for?
• What number do I call after hours and where do I go?
• If waters break at night, what should I do?
• Any restrictions on activity or intimacy?

3 tips for this week

1. Save every number. Clinician, hospital labor and delivery, partner, backup driver, backup childcare. Star them.
2. Rest when you can. Labor is coming; try to bank sleep. This is not the week to overcommit.
3. Time contractions when they arrive. A tool like Vyve makes this simple — start/stop with a tap, see the pattern.

How Vyve helps you track your pregnancy

Vyve is a privacy-first AI pregnancy and cycle tracker built for people who don't want their body's most personal data sold to advertisers. At 37 weeks, Vyve helps you time contractions, log kick counts, and note the small changes that could mean labor is close.

Vyve runs its AI on your device, encrypts your data, and doesn't require an account. Your pregnancy is yours.

Frequently asked questions

Is 37 weeks considered full term?

Under current terminology, 37 weeks is considered "early term" rather than full term. "Full term" means 39 to 40 weeks and 6 days. That said, babies born at 37 weeks usually do very well — you're inside the normal range for delivery. The distinction is why elective inductions or C-sections are typically discouraged before 39 weeks without a medical reason.

How big is baby at 37 weeks pregnant?

At 37 weeks, baby is about the size of a winter melon or a small watermelon — roughly 48 centimeters (18.9 inches) from head to heel, and weighing around 2.9 kilograms (6.4 pounds). Baby is still gaining weight and getting ready for arrival.

What does losing the mucus plug mean?

The mucus plug is a thick collection of mucus that seals the cervix during pregnancy. Losing it — sometimes called "bloody show" if tinged with blood — can happen in the weeks or days before labor. It's a sign that things are progressing, but labor could still be days or even weeks away. It's not a reason to rush to the hospital on its own, though it's worth mentioning at your next appointment.

How do I know I'm in real labor at 37 weeks?

Real labor contractions are regular, get progressively closer together, get stronger, and don't stop with rest or hydration. They usually start in the lower back and wrap around to the front. A common rule is 5-1-1: contractions 5 minutes apart, each lasting 1 minute, for at least 1 hour (or 4-1-1 for second-and-later births — call your clinician for their specific guidance). Waters breaking or any bleeding are also reasons to call now.

When should I go to the hospital at 37 weeks?

Go (or call your clinician) if: contractions match your team's 5-1-1 rule, waters break or persistently leak, you have any bleeding, decreased fetal movement, severe headache with vision changes, severe abdominal pain, or you feel something is very wrong. Your birth team gave you specific numbers to call — use them.

This article is educational and not medical advice. Always consult your obstetrician or midwife for personal medical guidance.