The real crux in this issue is whether there was any apparent damage to the baby following the fall on the floor;
if the baby yelled immediately and was not KOd, it would be very difficult to prove that damage occurred as the lawyers would simply argue that the fall had nothing to do with the baby's subsequent condition, whatever it turns out to be.
You really need eye witness accounts of the state of the baby both before and after the fall.
My guess would be that the baby suffered no damage as a result of the fall.
However, you do deserve an apology and some assurance from the hospital authorities that they have taken steps to avoid such a thing happening again.
if they fail to respond to your reasonable request for an apology and explanation, copy your correspondence to your MP, local councillor and health board chairman, stating that you will expect a response or you will take the matter further. LN