Thanks for posting query
Only falling from bed does not causes delayed physical or mental development. There must be some kind of internal head injury
to cause developmental problem which will be associated with some other symptoms also. If you are still worried then better consult a doctor for clinical evaluation.
I hope this answers your query effectively.
In case you have additional questions or doubts, you can forward them to me, and I shall be glad to help you out.
Please accept my answer in case you do not have further queries.
Wishing you good health.