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Learning to sit in infancy is a wonderful milestone anticipated by parents. Once an infant can sit, he or she can begin to play with toys, explore objects, and generally get more involved in the world around them. Independent sitting comes just before independent crawling, and is a necessary step before an infant learns to walk. Delays in sitting can signify problems in development, and often is cause for concern to parents. Here are some frequently asked questions about sitting development:

When will my baby sit by him/herself?

  • Although many people believe that sitting appears simply because of maturation, it is actually a skill that is learned. Sitting begins to emerge when the infant can hold their head steadily in a vertical position. Most infants start to prop sit after being placed in the position (see photo) around 4-5 months of age. But sitting independently varies from child to child based on many factors. And the trajectory of the development of control in the sitting posture varies from child to child. Some of these factors are:

  • -weight: in general, poor weight gain and growth is associated with slower developmental progress. Babies need good nutrition to develop the brain, muscles, and all body structures. There is no evidence that heavier infants have delays in sitting.
  • -strength: certainly infants need adequate strength in many muscle groups to learn to sit, primarily in the muscles of the head, neck, trunk and hips. However, usually learning to sit in infancy is more of a problem of coordinating the muscles, rather than developing extra strength.
  • -amount of practice: helping your infant to practice sitting, like in the picture, and helping your infant sit on your lap or the floor while reaching for toys is good practice for sitting. Like any other skill, practice makes perfect.
  • -amount of equipment use: related to the amount of practice, usually special equipment is not necessary to help an infant learn to sit. In fact, it is good to have the baby out of the infant seat to allow practice of movement control in an unrestricted way. Playing in many different positions is important for overall motor development.
  • -other factors influencing the development of sitting: how the infant is held or positioned most of the time, the willingness of the infant to use his/her arms for support, and the interest and temperament of the infant.

When should I be concerned if my infant is not sitting?
Most children sit independently without falling over by 7 or 8 months of age. If your baby is 9 months old and not yet sitting, you should talk to your pediatrician.How do I know if my infant is making progress in developing sitting?

Most infants start out propping, like in the picture below, between 4-5 months:

Then, around 5 months, they try to reach for things with 1 or 2 hands, and move their trunk into a tentatively balanced position to free their arms, like the infant below.

They make quite a few errors while practicing balancing without using their arms for support, but they are learning the whole time. Eventually, they can sit steadily and play without falling, as seen below.

If you are worried about your child developing sitting control, speak to your child's pediatrician. If he/she is also concerned, a referral to have a developmental evaluation can be provided, either through your local early intervention services or through developmental specialists.