Illustration of a baby at week 37 inside the womb in cross-section, with the placenta and umbilical cord — Womb in cross-section, enlarged to show detail. Not true size. Most babies are head-down by about 36 weeks.

Third trimester, week 37

37 weeks pregnant: Early term

Size of a: Winter melon
Length: 48.6 cm head to heel
Weight: 3.0 kg WHO median
Heart rate: 110–160 bpm typical range
Due date: 21 days away 93% of the way

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Checked against the sources listed on this page. Not reviewed by a clinician. Last updated 5 November 2026. How we check.

At 37 weeks pregnant, your baby is about the size of a winter melon: roughly 48.6 cm from head to heel, weighing about 3.0 kg. You’re in your third trimester, with about 3 weeks to go until your due date.

Your baby this week

At 37 weeks the baby is called “early term”.
They are rehearsing: inhaling fluid, sucking, gripping, blinking and turning towards light.
The brain and lungs are still maturing. That is why, if all is well, waiting for labour is usually preferred.

Your body this week

You may lose your mucus plug, a jelly-like discharge that can be tinged pink or brown. Labour can still be days or weeks away.
The cervix is softening and may start to thin (efface).
You may feel impatient, anxious or excited. All normal.

Typical weight gain so far: 10.3–14.5 kg
Your uterus: Near the ribs, may drop as baby engages

Weight gain range is for a pre-pregnancy BMI of 18.5–24.9 (IOM guideline). Your provider may advise differently.

Scans, tests and checkups

This week

Know your baby’s movements Self-care
Get to know your baby’s pattern. If movements slow down, change or stop, contact your maternity unit straight away. Don’t wait until the next day.
This week

Group B strep swab Self-care
A vaginal and rectal swab. If positive, antibiotics are given during labour. Routine in the US. The UK doesn’t screen routinely.
This week

Baby’s position check Checkup
Checks whether the baby is head-down. If they are breech, turning the baby from the outside (ECV) may be offered.
This week

Weekly checkups Checkup
Blood pressure, urine, growth, position and movements, plus planning for labour. Often weekly in the US. The NHS schedule is usually 36, 38 and 40 weeks.
From week 39

Membrane sweep & post-dates plan Checkup
A membrane sweep may be offered. If labour doesn’t start, induction is usually offered between 41 and 42 weeks.

See the full scan and test timeline

Real size, next to an adult hand

Adult hand 18.5 cmbaby 33 cm curled up

Growth curve

Typical weight by week: WHO median from week 20, approximate before that. Healthy babies vary widely.

When to call your midwife or doctor at 37 weeks

Call your midwife, doctor or maternity unit straight away, day or night, if you have any of these:

A change in your baby’s usual pattern of movement. Call straight away rather than waiting until the next day.
Vaginal bleeding, or a gush or steady trickle of fluid.
Severe belly pain that doesn’t go away.
A severe headache, vision changes, pain under your ribs, or sudden swelling of your face, hands or feet. These can be signs of pre-eclampsia.
Regular, strong contractions or your waters breaking. Follow what your maternity team told you about when to come in.
Intense itching, especially on your hands and feet, which can be a sign of a liver condition called cholestasis.
Fever of 38 °C (100.4 °F) or higher, or pain or burning when you pee.
Pain or swelling in one leg, chest pain, or sudden shortness of breath. These can be signs of a blood clot.
Feeling very low, hopeless or anxious most days. If you feel you might harm yourself, get emergency help.

Based on NHS and ACOG guidance. This list isn’t complete. If something feels wrong, call anyway. In an emergency, call your local emergency number.

Tip for this week

Learn when to go in. A common guide for first babies is contractions every 5 minutes, lasting 1 minute, for 1 hour. Go in any time your waters break, you bleed, or movements reduce.

Myth or fact?

Can spicy food or pineapple bring on labour?

Myth

There’s no good evidence that spicy food or pineapple starts labour. Some small studies suggest eating dates late in pregnancy may help the cervix ripen.

Read the evidence

Common questions at this stage

All common questions

Questions people ask about week 37

Is 37 weeks full term?

No. 37 weeks 0 days to 38 weeks 6 days is “early term”. Full term is 39 weeks 0 days to 40 weeks 6 days. Babies born at 37 weeks usually do well, but the extra weeks help the brain and lungs.

What does losing the mucus plug mean?

It’s a sign the cervix is changing. Labour could start within hours or weeks. Heavy, bright red bleeding is different and needs urgent care.

References

Advice differs between countries, so follow your own care team’s plan. Weights from week 20 are the WHO median, and earlier weights are approximate. How we check this.