Your baby at 4 months
Everything that lines up at this one age — growth figures from the WHO standard, sleep norms, the milestones whose normal window covers this month, and the vaccine doses due. Percentiles are called centiles in the UK; the numbers are identical.
Growth at 4 months
Median means half of babies are above and half below. Being away from the median is not a problem in itself — following your own curve is what matters.
| Median (50th) · Boys | Middle half (25th–75th) · Boys | Median (50th) · Girls | Middle half (25th–75th) · Girls | |
|---|---|---|---|---|
| Weight | 7.01 kg | 6.49–7.56 kg | 6.43 kg | 5.91–6.99 kg |
| Length | 63.9 cm | 62.5–65.3 cm | 62.1 cm | 60.6–63.6 cm |
| Head circumference | 41.6 cm | 40.8–42.4 cm | 40.6 cm | 39.7–41.4 cm |
Want the number for your own baby? Open the percentile calculator
Sleep at 4 months
Ranges, not targets. Healthy babies sit outside them regularly.
- Total per day
- 12 h – 16 h
- One nap
- 30 m – 1 h 30 m
- Night sleep
- 10 h – 12 h
Milestones in this window
The window is when a skill usually appears — not a deadline. Appearing later than the window is a reason to mention it at a check-up, not to worry alone.
- Holds head upGross motorusual window: 1–4
- Rolls overGross motorusual window: 3–6
- Sits unsupportedGross motorusual window: 4.5–8
- Grasps objectsFine motorusual window: 3–6
- CoosSpeechusual window: 1.5–4
- BabblesSpeechusual window: 4–9
- LaughsSocialusual window: 3–6
- Follows objects with eyesCognitiveusual window: 1–4
Vaccine doses at this age
Routine doses only, from the national schedules as published by each country's health authority. Vaccinations always follow chronological age, even for premature babies.
United States
- DTaPdose 2
- Hibdose 2
- Polio (IPV)dose 2
- Pneumococcal (conjugate)dose 2
- Rotavirusdose 2
United Kingdom
- DTaPdose 3
- Hepatitis Bdose 3
- Hibdose 3
- Polio (IPV)dose 3
- Pneumococcal (conjugate)dose 1
Reference figures, not medical advice. Every baby differs; a check-up answers questions a table cannot.