FirstWeeksYour baby at 17 weeks: four-month checkup
Medically-informed · Sources: CDC · Updated June 2026
Checkup and second vaccine round — plan a soft week around it while the sleep shift is still doing its thing.
What’s happening
The 4-month milestones
Around now most babies hold the head steady unsupported, push up to elbows in tummy time, laugh or squeal, and bring hands to the mouth constantly.
Vaccine day, round two
Same playbook as two months: brief crying, extra sleepiness or mild fussiness for a day is commonly seen. Feeding and holding right after the shots genuinely helps.
Rolling front-to-back
Many babies land the first full roll around now — usually tummy to back first, often to their own surprise.
What to do
- Bring your question list — the doctor visit sets in Ask can help
- Stop swaddling completely once rolling starts, if you haven't already
- Plan nothing ambitious for vaccine day
When to check in
After vaccines: fever above 104°F, inconsolable crying 3+ hours, or anything that worries you — call your pediatrician.
This is exactly what FirstWeeks shows you — matched to your baby
Week 17 guidance, skills to watch, and answers that know your baby’s age and log.
