I think it's easy to forget how difficult it was to see a doctor in the pandemic, and the woman had other children to add into the mix. They were scary times all round. In itself that is no excuse, but it could explain why she delayed. Also, people often put their heads in the sand in difficult situations and hope that things will sort themselves out somehow. Not wise of course, but maybe not worth going to jail for.
I feel desperately sad for the dead baby, and for the other children, but we don't know whether the woman was under duress from her newly reunited husband.
I can't understand why the judge refused to listen to mitigating circumstances either. I hope there is an appeal. Maybe she does deserve to go to jail (we don't know enough, and that's fair enough - she's going through enough without even more private details being made public), but at first glance it doesn't seem to me that she's been treated fairly.