A baby spine is soft and not yet fully developed. Babies should sleep on a surface that is neither too firm nor too soft. A mattress with good point-by-point elasticity gives your baby optimal support and relieves pressure on the spine.
This given your child’s spine the optimal conditions for development. On a mattress with point-by-point elasticity, your child won’t sink in to a dip. So, It will be able to move into its preferred sleep position on its own.