By Jennifer Riesmeyer, DPT

This study confirms that babies who are repositioned on their tummies instead of their backs, during their awake time, have 22% less gross motor delays. Functionally this means that the 6 month olds who were placed on their tummies more often were able to sit and roll sooner than those who were placed on their backs. Overall the babies placed on their backs also had lower motor skill scores on a standardized test than the other (tummy) group.

This baby is placed on her tummy so that she can develop stronger back extensor muscles. This means faster sitting up and rolling!

The simplest explanation is that in order to sit up, these babies had better balance between their tummy muscles and their back muscles. This allowed them to be more stable and hold their balance in an upright position in supported or independent sitting. If you prop your baby in sitting before they spend a significant amount of time on their tummy, their back muscles are not ready to counter balance their tummy muscles. Therefore you end up with a stiff baby in sitting (locked legs and trunk) or one that is flopped forward (back muscles can’t pull back baby back up to upright.)

Rolling is also an activity that requires both the tummy and back muscles working together. If your baby is always placed on her back, she only develops her abdominals to roll to her side. After she gets to her side, she needs her back extensor muscles to finish the roll from sidelying to tummy. These muscles are strengthened during tummy time.