The process of learning how to sit is one of many milestones for infants, and it happens in stages.
At first, babies gradually build their core strength by spending time on their backs and on their tummies. Play time that includes reaching, kicking, supporting their head, and stretching their limbs are all endurance building activities. As they grow stronger, you might even see some ab crunches! This is all good preparation for sitting!
The next step involves an infant rolling between their backs and their bellies which continues to build abdominal, leg, neck, and arm strength. Rolling belly to back usually comes first. Back to tummy usually happens around 6 months. They may seem like they are playing, but they are also practicing motor skills that will come into use later when they are mastering the art of sitting, standing, and then walking.
These months of muscle building lead to sitting up with assistance (usually between 4-6 months). You may hold them on your lap using your tummy as support, put them between your legs, or use a positioner around them on the floor for added support. If you use a positioner, make sure you always supervise. Always put your baby back into a sitting position if they topple over.
They will move from sitting with support to leaning forward on their arms for support, to relying solely on their core muscles (the ones that wrap around their torso) to help them sit erect for longer and longer periods of time. Play mats and toys can engage and encourage them to sit for longer periods of time. As much as possible, try to limit devices that put your baby into a sitting position.
Moving Into Sitting Position
As their gross motor development progresses, they will then be able to ease themselves into a sitting position on their own. Once they begin getting knees under their hips in an all 4’s position, rocking back and forth, scooting, and then eventually finding the coordination to crawl, they will more easily be able to shift their bodies into a sitting position.
If you are worried about your baby and sitting, contact our Family Help Line at 1-800-932-4673 or sign up for a developmental screening! https://www.parenttrust.org/for-families/developmental-screenings/