40 Weeks Pregnant: Baby Size, Symptoms and Signs of Labor

At 40 weeks pregnant, you have reached your estimated due date. Your baby is fully developed and ready for life outside the womb, although many pregnancies naturally continue for several more days before labor begins.

Only about five percent of babies are born on their exact due date, so it is very common for pregnancy to continue beyond this point.

If you are searching for 40 weeks pregnant baby size, symptoms, or when labor will begin, this stage is a time of readiness and patience as your body completes the final preparations for birth.

At a Glance:
40 Weeks Pregnant
  • Baby size: about the size of a small pumpkin
  • Trimester: third trimester
  • Key hormonal shift: oxytocin helps stimulate and regulate labor contractions.
  • Common symptoms: pelvic pressure, frequent urination, Braxton Hicks contractions, lower back discomfort, swelling in the feet or ankles, and difficulty sleeping.
  • Doctor visit: weekly prenatal visits continue and providers may discuss monitoring if pregnancy continues beyond the due date
  • Emotional theme: anticipation and patience as you wait for labor to begin.

At 40 weeks pregnant, your baby measures about 50 to 52 cm from head to heel and weighs around 3.3 to 3.6 kilograms (about 7.3 to 8 pounds).

Here is what is happening:

• the lungs are typically mature and ready for breathing after birth
• the brain continues developing and will keep growing after birth
• body fat supports temperature regulation outside the womb
• reflexes such as sucking, grasping, and blinking are strong
• the digestive system is prepared to process milk
• the immune system continues receiving protective antibodies from the mother
• most babies remain positioned head down

Your baby is fully prepared for the transition to life outside the womb.

What Is Happening in Your Body at 40 Weeks Pregnant

Even though you have reached your due date, labor may still begin naturally within the coming days.

You may notice:

• increased pelvic pressure
• stronger or more frequent contractions
• lower back discomfort
• swelling in the feet or ankles
• frequent urination
• difficulty sleeping comfortably

Your cervix may continue softening, thinning, and gradually dilating as your body prepares for labor.

Babies should continue moving regularly at 40 weeks, even though movements may feel slightly different because space inside the uterus is limited.

Signs Labor May Be Starting

During the final days of pregnancy, several signs may indicate that labor is beginning.

These may include:

• regular contractions that become stronger and closer together
• lower back pain that comes in waves
• loss of the mucus plug
• bloody show (blood-tinged mucus discharge)
• rupture of the amniotic sac, often called water breaking

These signals may appear gradually or suddenly as labor begins.

Emotional and Nervous System Changes

Reaching the due date can bring a mix of emotions.

You may experience:

• excitement about meeting your baby
• impatience as the waiting continues
• heightened awareness of physical sensations

Supporting calm breathing and rest can help maintain emotional balance during this final stage.

3 Focus Areas This Week

Stay attentive to body signals
• contractions may gradually become more regular

Protect rest and energy
• conserving energy can support the work of labor

Maintain calm breathing
• relaxation and breathing practices can help keep your nervous system steady.

Weekly Calm Practice

Sit comfortably and place one hand on your belly.

Take a slow breath in through your nose and feel your belly gently rise.

Exhale slowly and allow your body to soften.

Notice the steady rhythm of your breath and the quiet presence of your baby.

Take several calm breaths and allow your body to relax.

Preparing for Birth

As labor approaches, maintaining a calm and focused mindset can help support the birth experience.

Techniques such as hypnobirthing emphasize breathing, relaxation, and working with the body’s natural rhythms during labor.

The MamaZen app includes guided hypnobirthing sessions designed to help support calm, confidence, and emotional steadiness during birth.

This Week’s Guided Episode

Listen to this week’s episode of the Pregnancy Week by Week Podcast for a deeper explanation of 40 weeks pregnant development and a guided moment of calm as you await the beginning of labor.

Coming soon.

If Labor Has Not Started Yet

It is common for pregnancy to continue beyond the due date.

Many babies are born between 40 and 41 weeks, and your healthcare provider may recommend additional monitoring such as nonstress tests or ultrasounds if pregnancy continues longer.

Your provider will guide you on next steps if labor has not yet begun.

Supporting Calm as Birth Approaches

As the final days of pregnancy unfold, emotional steadiness can support both your body and your baby.

MamaZen offers guided sessions designed to support:

• relaxation before labor
• emotional balance
• sleep during late pregnancy
• hypnobirthing preparation

Support during pregnancy is not only physical. It begins with calming your internal state.

Frequently Asked Questions

40 Weeks Pregnant: Baby Size, Symptoms and Signs of Labor

How big is the baby at 40 weeks pregnant?
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At 40 weeks pregnant, your baby measures about 50 to 52 cm from head to heel and weighs around 3.3 to 3.6 kilograms.

Is it normal to go past the due date?
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Yes. Many pregnancies continue several days beyond the estimated due date before labor begins naturally.

How will I know labor has started?
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Signs may include regular contractions, lower back pressure, loss of the mucus plug, or water breaking.

Should the baby still move at 40 weeks pregnant?
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Yes. Babies should continue moving regularly. If you notice a significant decrease in movement, contact your healthcare provider.

At 40 weeks pregnant, you have reached the final milestone of pregnancy.

Your baby is ready for birth, and your body is completing the final steps of preparation.

Move forward with calm awareness as you prepare to welcome your baby into the world.

Written by Irin Rubin

Founder of MamaZen

Disclaimer

This content is for informational purposes only and does not replace medical advice. Always consult your healthcare provider with questions about your pregnancy.