Sitting is an early developmental milestone on the way to standing, walking, and other motor skills that help a baby move and explore the world more easily.
Sitting can make it easier for babies to play games and to interact face-to-face.
According to the Centers for Disease Control and Prevention (CDC), most babies can sit without support after around 6 months and move into a sitting position after about 9 months.
However, each baby is different, and some may take less or more time to sit up by themselves.
The earliest sitting milestone is when a baby can sit unsupported. A caregiver might put the baby in a sitting position, and the baby then remains in that position.
Many babies master this skill at around 6 months. If a baby cannot do this by the time they are about 1 year old, it does not necessarily mean they have a developmental issue or another health issue.
However, parents or caregivers who are worried about any aspects of the baby’s development can talk to a doctor or pediatrician.
By 9 months, many babies begin getting into a sitting position without support. They may push themselves up from their bellies or rollover after crawling, then push into unsupported sitting.
Before a baby can sit up on their own, they need good head control. According to the CDC, most babies achieve this at around 4 months. At about 2 months, many babies begin holding their heads upright for short periods when pushing up from their stomachs.
Babies also need to exercise their arms, abdominal muscles, backs, and legs, since they use all of these muscles to get into a sitting position or support themselves when sitting.
Research shows that biological factors, such as a developing brain and body, and cultural and environmental factors, play a role in when a baby learns to sit up by itself.
For example, according to the Academy of Pediatric Physical Therapy, children in some cultures sit earlier than others. Compared to infants in the United States and some other nations, infants in Kenya and Cameroon sit earlier — usually around 5 months. This may be because the parents and caregivers give these babies more opportunities to practice sitting skills.
When a baby sits up depends in part on the environment where they grow up. Babies whose caregivers find ways to motivate sitting and encourage them to develop strong muscles may sit earlier and then begin achieving other milestones, such as pulling up on objects and walking.
These strategies can help:
- give newborns regular tummy time while awake so that they can practice head control and pushing up on their arms
- make tummy time fun by shaking rattles, talking to the baby, and giving them things to reach for
- place toys near the baby that they can reach out for them
- play with, read to, and sing to the baby to encourage interaction with adults, and they may want to sit up and master other motor skills
- respond to the baby’s babbling, and to their attempts to talk and play
- help the baby into a sitting position and offer them only as much support as they need to remain in the position
- support the baby into a sitting position and play face-to-face games, such as peek-a-boo
- give the baby toys or books to look at when in a sitting position
Do not leave a baby playing unattended, including when sitting up. While baby seats may offer support, a baby should not sit in these seats alone.
Every baby develops differently. Babies born prematurely tend to develop more slowly than their peers, especially during the first year of life.
Doctors often assign them a “corrected age” based on how prematurely they were born. Some preterm babies develop specific skills later. For example, a baby born 2 months early may not be at the same stage as other 2 month-old babies born at full-term.
According to the CDC, a baby might need additional help if:
- they are not sitting up by 12 months or 12 months, according to their corrected age
- they are falling significantly behind on the developmental milestones they must achieve to sit up, such as not lifting their head by 2 months or controlling their head by 6 months
- they seem very stiff or have trouble coordinating their movements
- do not exhibit social behavior, such as smiling at caregivers, making eye contact, or seeking to interact with caregivers
- are not reaching for things, responding to sounds, laughing, or rolling over in at least one direction by 6 months
Early intervention when a child has a developmental delay can help the child get back on track.
Many states offer free early intervention services, so ask a pediatrician about eligibility for these services. In most cases, the child’s primary care doctor can flag a problem and then refer them to a specialist, such as a developmental pediatrician, for further diagnosis.
It can be exciting when a baby starts to sit because it makes it easier to talk to the baby while making eye contact. Babies who sit may soon cultivate other skills, like crawling or pulling up on objects.
Every baby develops according to their own timeline, and caregivers should not pressure babies to do things they are not ready to do. However, a little support and encouragement might help a baby to sit earlier.
It is never too early to talk to a pediatrician. Anyone who has concerns about a baby’s development should seek support as early as possible.