Pregnancy Guide

18 Weeks Pregnant

Your baby is the size of a Bell Pepper. Discover exactly what is happening to your body and your baby this week.

New pregnancy guide: Learn how weeks are counted, what each trimester means, and how to interpret your calculator results for better preparation and planning. Read the full guide

Week 18 in detail

Nerves get myelin — book the anomaly scan

Baby this week

The nervous system is wrapping fibres in myelin (insulation). Yawns, stretches, and sucking show up on scan. Length is still crown-to-rump. The 20-week anatomy scan should already have a date.

  • Myelin is a long project — it continues after birth
  • The baby can hear your voice as a rumble
  • Genitals may be visible; “gender” on scan is anatomy, and it can be wrong

Your body this week

A heavier bump makes lying flat on your back a bad habit (the uterus can press the big vein). Tilt with a pillow. Heartburn and a stitch under the ribs appear. Maternity leave paperwork has earlier deadlines than people think.

  • Back-sleeping that feels fine for five minutes can still drop blood pressure — roll left
  • Write leave dates down; HR will not chase you
  • If you want a support person at the anatomy scan, book them now

Get ready for the anatomy scan

Confirm the 20-week anomaly scan. It checks organs, not your parenting. The checklist above is the date, sleep position, and leave. Bring a snack; these scans run long when the baby hides a kidney.

A general guide, not medical advice. Scan timing and symptoms vary — ask your clinician.

Baby Growth Curve

This chart visualizes the average length of the baby from week 1 to 40. Values are based on standard clinical averages.

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