Your baby at 21 weeks
The baby continues practising movements and swallowing amniotic fluid. Growth remains steady.
Fine body hair and the protective skin coating continue developing.
TRIMESTER 2 · WEEK 21
21 weeks pregnant
Finding a rhythm.
What to expect at 21 weeks pregnant: your baby, your symptoms and this week’s reminders.
Symptoms at 21 weeks pregnant
- You may notice a more familiar movement pattern.
- Backache or heartburn may occur.
- Your legs may feel tired.
None of these symptoms is required. Symptoms alone cannot diagnose pregnancy or establish your baby’s wellbeing.
Get to know your baby’s usual movements. Contact your team immediately if they reduce or change.
Source for this week: NHS — Week 21
Measurement note: early lengths are head-to-bottom; from week 20 they are head-to-heel. The numbers across that change should not be compared as if the measurement method were the same.
YOUR WEEK, YOUR JOURNEY
Explore another pregnancy week
Choose a week to explore your baby’s development and changes you may notice.
01 · FIRST TRIMESTERSmall beginnings
02 · SECOND TRIMESTERA growing connection
03 · THIRD TRIMESTERGetting closer to meeting
Sources and content note
This is source-based general information, not a substitute for a clinical assessment or individual care plan. The presence, absence or change of symptoms alone cannot establish pregnancy wellbeing. This content is not a personalised care plan reviewed by a healthcare professional.
This guide groups weeks 1–13 in the first trimester, 14–27 in the second, and 28 onwards in the third. Weeks refer to gestational age dated from the last menstrual period; clinical dating may differ.
- NHS — Pregnancy week by week
- ACOG — Fetal development and gestational age
- NHS — Your baby’s movements
- NHS — Pregnancy symptoms
Sources checked: 31 October 2026 · Illustrations are AI-generated conceptual drawings, not ultrasound or diagnostic images.