Sitting without support
Most babies sit on their own at around 6 months. Nearly all healthy children sit without support somewhere between about 4 and 9 months.
How sure are we?
Fairly sure. Two large studies in nine countries agree, but only two have been read so far. How we know this
What it’s a sign of
Your baby has the strength and balance to hold themselves upright, which frees their hands to play.
How early babies sit depends partly on how often they're given the chance: at 5 months, nearly all babies filmed in Cameroon sat on their own, against about 1 in 6 in the United States. Differences between countries were larger for sitting than for walking.
We don't know how much time spent in baby seats affects sitting.
A main source for the ages
WHO Motor Development Study: Windows of achievement for six gross motor development milestones
WHO Multicentre Growth Reference Study Group · 2006 · Acta Paediatrica
- Children
- About 800 children
- Where
- Ghana, India, Norway, Oman and the United States
- Ages
- 4 months to 2 years
- How
- Trained researchers tested the same children every month or two, and parents noted the dates too
- What it found
- The World Health Organization followed about 800 healthy children in five countries and measured when they first sat, crawled, stood and walked. Nearly all children walked on their own between about 8 and 18 months, and about half by their first birthday.
- Limits
- All the children were healthy and growing well, so the windows describe healthy children. The study stopped at 2 years.
A main source for the ages
Similarities and differences in child development from birth to age 3 years by sex and across four countries: a cross-sectional, observational study
Ilgi Ozturk Ertem, Vibha Krishnamurthy, Mphelekedzeni C. Mulaudzi, Yanina Sguassero, Hakan Balta, Ozlem Gulumser · 2018 · Lancet Global Health
- Children
- About 4,900 healthy children
- Where
- Argentina, India, South Africa and Turkey
- Ages
- Birth to 3½ years
- How
- Trained staff asked parents open questions about what their child could do, at health clinics
- What it found
- Found the age by which half of children reached more than 100 milestones. Most came at similar ages in all four countries, and for boys and girls. For example, half of children waved bye-bye by about 11 months and said a first word by about 9 months.
- Limits
- Only four countries and no rural areas, children from city clinics, and only healthy children (about half of those who came were left out for health reasons). It gives the age for half of children, not the full spread.
A main source for the ages
Assessment of sex differences and heterogeneity in motor milestone attainment among populations in the WHO Multicentre Growth Reference Study
WHO Multicentre Growth Reference Study Group · 2006 · Acta Paediatrica
- Children
- About 800 children
- Where
- Ghana, India, Norway, Oman and the United States
- Ages
- 4 months to 2 years
- How
- Compared boys with girls, and the five countries, in the same children
- What it found
- Boys and girls reached these milestones at the same ages. There were some differences between countries, probably from different ways of caring for babies, and Norwegian children were latest on average for all six.
- Limits
- Same children as the main WHO study, so it isn't an independent second source.
A study that questioned earlier findings
Places and Postures
Lana B. Karasik, Catherine S. Tamis‐LeMonda, Karen E. Adolph, Marc H. Bornstein · 2015 · Journal of Cross-Cultural Psychology
- Children
- About 70 babies
- Where
- Argentina, Cameroon, Italy, Kenya, South Korea and the United States
- Ages
- 5 months
- How
- Researchers filmed babies at home for an hour
- What it found
- At 5 months, about 1 in 3 babies sat on their own at least briefly, from none in Italy and about 1 in 6 in the United States to 11 of 12 in Cameroon. Babies in Kenya and Cameroon, who were often sat on the ground or furniture with little support, sat alone most.
- Limits
- Only 12 babies per country, filmed for one hour.
A study that questioned earlier findings
Environmental Effects on Motor Development: the Case of ‘African Infant Precocity’
Charles M. Super · 1976 · Developmental Medicine & Child Neurology
- Children
- About 60 babies
- Where
- Rural Kenya
- Ages
- First year
- How
- Researchers studied babies and their families closely
- What it found
- Babies sat and walked early by American standards, and these were the skills their carers taught and practised. They weren't ahead on skills that weren't practised.
- Limits
- We have only read the summary, which gives no ages.
If you’re worried about your child, talk to your child and family health nurse or GP.
Last checked 2 November 2026