Your baby at 3–4 months: what to know and when

These are the tips Coo starts showing parents when a baby is three to four months old.

Health

The 4-month checkup is coming up

There's usually a checkup around 4 months, where baby may get the next round of vaccines. Booking a little ahead makes it easier to find a time that suits you both.

Your doctor or pediatrician can tell you what to expect at this visit.

Sources

American Academy of Pediatrics · AAP Schedule of Well-Child Care Visits
American Academy of Pediatrics · Checkup Checklist: 4 Months Old
Public Health Agency of Canada · Provincial and territorial routine and catch-up vaccination schedule for infants and children in Canada

Checked against sources Nov 7, 2026

Sleep

Bumpier nights around 4 months are normal

Around 4 months, baby sleep starts settling into more grown-up cycles, and many families find nights get bumpier for a while. It's a normal stage, and putting baby down drowsy but still awake can help them learn to settle on their own.

Sources

American Academy of Pediatrics · Getting Your Baby to Sleep

Checked against sources Oct 12, 2026

In the Coo app, these tips appear in Explore, timed to your baby’s age.