they strap arms for venous access (so they can put a drip in you) if you have poor access (like because you have been in labour for ages and had like intake) they may need your arms to be still.

neither of my arms were strapped down however. the BP cuff on one arm made it feel like it, but i could move them.
I was able to hold MJ for a little while and then she was taken away and my DH left too