Your baby is 4 weeks old — you have officially survived the first month, and your little one is changing right before your eyes.
What's Happening This Week
One month in, your baby's reflexes are stronger and their movements are beginning to show the first hints of intentionality. During tummy time, many babies can now lift their head briefly at a 45-degree angle. Their arms and legs are starting to uncurl from the tight fetal position, and their movements, while still largely uncoordinated, are becoming smoother. You may notice your baby stretching more, kicking with greater force, and bringing their hands closer to their face with increasing frequency.
Visually, your baby is making real progress. They can now track a moving object more smoothly across their midline, and their focusing distance is expanding slightly beyond that initial 8-to-12-inch range. Colors are starting to become more distinguishable — they can now detect bold, saturated colors like red and yellow in addition to the high-contrast black and white they have preferred until now. Your baby's hearing is increasingly sophisticated, and they may show clear preferences for certain sounds, voices, or types of music.
Socially, this is an exciting week. Your baby is on the cusp of their first true social smile — some babies achieve it right at four weeks, while others will get there in the next week or two. You may see proto-smiles during sleep or in response to your voice that are not quite the real thing yet but feel magical nonetheless. Crying typically continues to increase and may peak in the coming weeks. Sleep is still fragmented, though some babies begin to consolidate slightly longer stretches at night.
Play Ideas for Week 4
- Color introduction: Introduce a brightly colored toy — red or yellow works best. Hold it within focusing range and let your baby study it. Slowly move it side to side.
- Tummy time with motivation: Place a high-contrast image or mirror at your baby's eye level during tummy time. Having something interesting to look at encourages them to lift their head.
- Talking in turn: When your baby makes sounds (even just grunts or sighs), pause and respond as if you are having a conversation. This early turn-taking lays the groundwork for language development.
- Gentle bicycle legs: While your baby is on their back, gently move their legs in a bicycling motion. This can help with gas discomfort and also gives them sensory input about how their body moves.
- Different positions: Hold your baby in different orientations — upright against your shoulder, cradled in your arms, facing outward while supported. Each position gives them a different view of the world.
What You Need
At four weeks, tummy time is becoming a real daily practice. A well-designed tummy time mat with engaging visual elements can make these sessions more enjoyable for both of you. Our mats are built to support this exact stage of development — browse the collection at /collections/tummy-time-mats.
When to Talk to Your Pediatrician
Your one-month well-visit is likely happening this week. Come prepared with questions about feeding, sleep, and anything that has concerned you. Between visits, contact your pediatrician if your baby seems unable to focus on your face at all, does not startle in response to loud sounds, or if their body seems unusually stiff or unusually floppy.
This post is for informational purposes only and is not a substitute for professional medical advice.
For a complete overview, read our ultimate baby play mat guide.
FAQ
Is it normal that my 4-week-old has not smiled yet?
Absolutely. The first social smile typically appears between four and eight weeks. Every baby has their own timeline. If your baby is making eye contact, responding to your voice, and showing other signs of engagement, they are right on track.
How long should tummy time be at 4 weeks?
Aim for three to five minutes per session, working up to a total of 15 to 20 minutes spread throughout the day. Short, frequent sessions are better than one long one. Follow your baby's cues — if they are getting frustrated, take a break.
Previous: Week 3 → | Next: Week 5 → | Back to all weekly guides →
Shop tummy time mats →