YANBU to have sympathy for them, but personally I have none. I do think, though, that there should be more focus on the editorial team around them.
This radio station decided to take a hospital admission for a serious condition (bear in mind, before drips, etc, people died of HG. Charlotte Bronte is believed to have done). They knew nothing about the rest of her condition - she could have been miscarrying, or dangerously close to organ failure, for all they knew.
They decided that someone in that position was an appropriate focus for a prank. Somehow, because she was royal/famous, she was not a person. Would you 'prank' a friend or relative in those circumstances, even if they liked jokes?
They then decided that it was ok to involve staff at the hospital in their 'prank' by calling them. Even on the best case scenario for the hospital, they would have wasted the time of hospital staff.
They called, and they heard what happened. Personal details of a sick woman were revealed (even if most of it was in the public domain as, thankfully, it was good news). A second's pause at that point would have made them realise that nothing good could happen for the staff involved. The apparent suicide was not foreseeable, but shame, and embarrassment and ridicule were all obvious consequences. So they thought it was ok to publicly shame and humiliate someone. Disciplinary action against the staff could easily have followed. Likewise, how does it make someone who has spent the last x days chucking her guts up until dangerously dehydrated feel that her condition has been the focus of such hilarity.
Knowing that, they went ahead and broadcast, trailed, promoted and boasted about their 'prank'. They said 'oops, sorry' when challenged, but continued to promote, and brag, about the prank. Until the awful news.
All those at the station involved have been guilty of treating the nurse, the staff and the royals as 'non persons' just because of the press interest in the pregnancy. They treated them in a way you would never treat someone you knew, in a way you would never want anyone to treat your mum, or sister, or friend. I hate all 'pranks', but it's just not the same as convincing Justin Beiber he's promoting trainers with a rude name or whatever. It was deeply cruel from the outset.
And because it was cruel from the outset, I don't really have much sympathy with the (admittedly unforeseeable) consequences. Because when you are cruel to people, sometimes you hurt them more than you realise.
As for those who said, 'Charles was laughing about it', I expect he felt he had no choice but to laugh along. I knew bullies at school who did this. Played nasty tricks on people and, if you didn't laugh, you 'had no sense of humour'. It was their automatic joke. 'Duh, it was a joke, can't you take a joke'. If Charles had said 'well actually no, what they did was despicable' he would have made this into a bigger story than it was at the time "Charles condemns prank call" headlines. So my guess is he smiled and joked as the least worst way to answer.