Your baby at 1 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 1 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 | 4.45 kg | 4.06–4.87 kg | 4.17 kg | 3.80–4.57 kg |
| Length | 54.7 cm | 53.4–56.0 cm | 53.6 cm | 52.3–54.9 cm |
| Head circumference | 37.2 cm | 36.5–38.0 cm | 36.5 cm | 35.7–37.3 cm |
Want the number for your own baby? Open the percentile calculator
Sleep at 1 months
Ranges, not targets. Healthy babies sit outside them regularly.
- Total per day
- 14 h – 17 h
- One nap
- 30 m – 2 h
- Night sleep
- 8 h – 9 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
- CoosSpeechusual window: 1.5–4
- First smileSocialusual window: 1–3
- 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
- Hepatitis Bdose 2
Reference figures, not medical advice. Every baby differs; a check-up answers questions a table cannot.