IF GUILTY
I think the circumstantial evidence alone is overwhelming. It's just the fact she was there for each of the collapses which allegedly had no identifiable cause, and nobody else was. The only person close to that was present at just 7 out of the 22. She was there for all 22!!! These are undisputed facts.
Colleagues remarked on this after just the first few babies - poor you, it always seems to happen on your shift.
That is why the police were asking, how could this be? Bad luck? Coincidence? Or are you the perpetrator?
Unless there was a team of baby killers on the ward, I think this is the case of Occam's razor - the simplest solution is the most likely.
IMO