Baby development at week 21
Bone marrow takes on blood-cell production. Taste buds mature. Eyebrows and lids are more defined.
Average size estimates for week 21 are about 26.7 cm and 360 g — roughly carrot. Your ultrasound report and clinician’s dating override any website average.
What you might feel
You might feel jabby movements after meals or at night. Sleep can get lighter.
You are in the second trimester. Two pregnancies at the same week can feel completely different — treat these notes as orientation, not a checklist you must match.
Noticing movement in week 21
Flutters often become clearer around mid-pregnancy, though timing varies widely. You do not need a formal count yet for every pregnancy — casual awareness is enough. When patterns feel regular later, Preglo’s kick counter is ready without a separate app.
What to track this week
- Symptoms, mood, sleep, and energy in your daily log
- Water intake toward a simple daily goal
- Appointment dates and questions for your care provider
- Scan dates and follow-up notes after ultrasound visits
A calm next step in Preglo
Use the daily log for sleep quality; it often explains next-day energy better than memory alone.
Also useful: due date calculator · all weeks · Preglo features
Nearby weeks: Week 19 · Week 20 · Week 22 · Week 23
Educational averages only — not medical advice. Contact your clinician for symptoms that worry you, bleeding, severe pain, or reduced movements.