Week 21 of pregnancy

21 Weeks Pregnant

Second trimester

Baby size

About the size of a carrot

26.7 cm

What's developing

The baby's movements are becoming more coordinated. Taste buds are developing on the tongue.

Common symptoms this week

  • Braxton Hicks may start
  • Stretch marks
  • Warmer skin
  • Backache

This is an estimate for information only — only about 1 in 20 babies arrive on their due date. Always confirm dates with your midwife or doctor.

How big is a baby at 21 weeks?

Baby growth chart

Typical fetal length and weight from week 8 to week 40.

Weeks 8–40

Length

cm

Week 21: 26.7 cm

0153045816243240crown–heel →

Weight

grams

Week 21: 360 g

0500g1.5kg3kg816243240

Typical averages based on Hadlock / ACOG references. Weeks 8–20 use crown–rump length; weeks 21–40 switch to crown–heel — that's the small jump you'll see mid-chart. Real babies vary — your ultrasound is the reliable number for you.

Frequently asked questions

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