Baby by Week
Week 18

Your week 18 guide

The nervous system, hearing, bones, and movement are all becoming more sophisticated.
Trimester

2

Month

5

Weeks left

22

Size at a glance

Comparison
Carrot
Length
14 cm
Weight
7 oz
Measurements are approximate. Healthy babies grow at different rates.

Baby development

Myelin is beginning to coat developing nerves so signals can travel more efficiently.
The brain has developed roughly 100 billion neurons during the first four months.
Nerve endings and the forming bones of the inner ear let your baby hear your heartbeat, blood flow, and digestive sounds.
Bones are starting to harden through ossification, beginning in areas such as the collarbones and legs.
Movement can include twists, turns, stronger kicks, and yawns.

Your body

You may begin noticing movement, although the timing of first movements varies between pregnancies.
Backache and muscle pain can increase as relaxin loosens joints and ligaments and your posture changes.
Leg cramps, nosebleeds, varicose veins, and disturbed sleep can occur.
Fluid retention may cause swelling in your hands or feet; contact your clinician about severe or rapidly increasing swelling.

This week's checklist

Ask your care team whether your iron intake meets your needs.
Include calcium-rich foods and continue the prenatal supplements recommended for you.
Prioritize sleep and adjust your exercise routine for your changing balance and body shape.
Make time to connect with your partner and begin planning your baby-shower guest list if you want one.

Call your care team

Contact your clinician for bleeding, fluid leakage, severe or rapid swelling, or persistent pain.
Seek urgent help for severe headache with vision changes, chest pain, fainting, or trouble breathing.

Medical information, not medical advice

Every pregnancy is different. Use this guide for general education and follow the advice of your own maternity care team. Do not delay urgent care because of something you read here.