Mamamau,
I couldn't tell you the brand anymore but it just had to do with the fact that my first daughter was too thrilled to play with the ball (we had it ready a few days before birth already!) and she just pinned it...and with my 'weight' afterwards, it just didn't make it!!
but maybe can you check with the hospital if they can provide you with one as mamalicious mentioned it?
for me, it was only for home as I only wanted to go to hospital at the last moment.
when is your DD?