Hi Cheryl
I m a physio who is interested in paeds altho I havent formally worked in the area, lots of casual reading n m a mom of a 4 m.o. myself.
All babies have thier own rate of development n as they say will do things in thier own time! However, it is helpful to assist n enc thier dev thru activities.
There r specialised physios who work in the area of paeds n they can perform developmental assessments to see if the child is working towards certain dev milestones. They can also suggest activities to stimulate the development of muscle n movement.
Unless there r underlying causes that may be hindering normal development (many causes - sensory probs eg hearing, visual difficulties etc, muscle weakness etc), all children are presumed to be able to achieve their dev potential in time. So its impt to assess 4 n rule out any such causes, them work toward strategies 2 promote dev.
sorry 4 one-handed typing - bubs sleeping in the other arm!
Hope this hepls