How to Calculate Your Baby's Exact Age in Weeks and Months
In the first months of life, a baby's age is often expressed in weeks rather than months. This is because development is so rapid that even a few days make a difference.
Why Count in Weeks
Pediatricians use weeks for several practical reasons:
- WHO growth charts for the first months are calibrated on weekly intervals
- Developmental milestones are assessed with weekly precision
- Vaccination schedules indicate doses in weeks (e.g., first hexavalent dose at 8 weeks)
- Feeding changes rapidly: formula amounts and feeding frequency adjust week by week
Key Developmental Milestones
Every baby develops at their own pace, but there are indicative milestones:
- 1 month: first social smile, begins to fixate on faces
- 2 months: follows objects with eyes, makes cooing sounds
- 3 months: holds head steady, discovers own hands
- 6 months: sits with support, begins solid food introduction
- 9 months: crawls, responds to own name
- 12 months: first steps, first intentional words
- 18 months: walks confidently, vocabulary of 10-15 words
- 24 months: two-word sentences, runs
- 36 months: fluent language, structured symbolic play
When to Be Concerned
Individual variations are wide and normal. However, consult your pediatrician if the baby hasn't reached certain fundamental milestones by maximum limits: no social smile by 3 months, no head control by 5 months, not sitting by 9 months, not walking by 18 months.