Overview
Week 21 brings fresh changes as your baby grows. About 4–5 months is a season of tiny wins — a new sound, a longer stretch of sleep, or a smile that melts the exhaustion.
Infant · Weeks 13–26 · About 4–5 months
Your 21-Week-Old Baby
At 21 weeks (about 4–5 months), your baby is learning every day. Here is what many families notice.
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Baby Development
This week, typical development may include: May army-crawl or scoot, responds to name sometimes. Every baby follows their own timeline — comparison is the thief of joy.
Milestones
May army-crawl or scoot, responds to name sometimes.
Sleep
Two to three naps plus longer night sleep are common. Regression weeks can still happen.
Feeding
If solids have started (often around 6 months), milk remains the main nutrition while textures expand slowly.
Health & Wellness
Teething may begin — drooling and gnawing are common. Offer safe teethers.
Partner & Family Support
Share night feeds, nappy changes, or a short walk so the primary caregiver can rest.
When to Call the Doctor
Call your paediatrician for fever in a young baby, fewer wet nappies, breathing difficulty, persistent vomiting, or if something feels wrong to you.
Frequently Asked Questions
Sleep varies enormously in the first year. Short cycles, cluster feeding nights, and growth spurts all shake things up. Track overall mood, feeding, and wet nappies — and ask your doctor if you are worried.
ParentVibes Tip
Capture moments, but also rest when baby naps if you can.
ParentVibes offers general information, not medical advice. Always follow your paediatrician.