Sitting independently gives your baby a new perspective on the world. Once your baby's back and neck muscles are strong enough to allow for sitting upright and he or she has figured out where to put those legs to avoid toppling over, it's just a matter of time until the next phase – crawling, standing, and walking.
When it developsYour baby will probably learn to sit independently between the ages of 4 and 7 months. This is about the same time that your baby will master rolling over and holding his or her head up. About 90 percent of babies can sit well for several minutes without support by the time they're 8 months old. (Even babies who've mastered sitting will topple over eventually, often because they lose interest in being upright.)
How it develops
While you can prop your baby in a sitting position almost from day one, true independent sitting doesn't begin until head control has been mastered. Starting at about 4 months, your baby's neck and head muscles strengthen rapidly, and your baby will learn to raise and hold his or her head up while having tummy time.
Next, your baby will figure out how to prop up on his or her arms and will hold his or her chest off the ground in sort of a mini-pushup. By 5 months, your baby may be able to sit momentarily without assistance, though you should stay nearby to provide support and pad the surrounding area with pillows to cushion a possible fall.
Soon your baby will figure out how to maintain balance in the sitting position by leaning forward on one or both arms. By 7 months, your baby will probably be able to sit unsupported (which will free his or her hands for exploring) and learn how to pivot to reach a desired object while sitting. At this point your baby may even be able to get from the tummy-time position into a sitting position by pushing up on his or her arms. By the time your baby is 8 months old, he or she will likely be sitting well without support.
You can guess what comes after your baby figures out that he or she can lunge forward from a sitting position and balance on hands and knees. Your baby may get the hang of moving forward (or backward) on all fours as early as 6 or 7 months, and master crawling by 10 months. At this point your child is both very mobile and very curious, so childproofing is very important.
By the way, most pediatricians recommend waiting until your baby is sitting with minimal support before introducing solid foods.
During tummy time, use a bright toy that makes noise or a mirror to encourage your baby to look up. Lifting his or her head and chest helps your baby strengthen neck muscles and develop head control.
Once your baby is a fairly confident sitter, put toys and other intriguing objects just out of reach – they'll be a good attention-grabber as your baby learns to balance with his or her arms.
When to be concerned
If your baby doesn't have steady head control by the time he or she is about 6 months old and hasn't started learning to prop up on his or her arms, bring it up with your child's doctor. Babies develop skills differently, some more quickly than others, but head control is essential to sitting independently, and sitting is the key to crawling, standing, and learning to walk. Keep in mind that premature babies may reach this and other milestones later than their peers.