Why a cat can give birth to dead kittens?
There are many reason a cat will deliver still born kittens. First, consider if it was her first litter it is more likely to happen. She is inexperienced and didn’t deliver them in time. Second if she is very young and pregnant or very old and pregnant it is more common because it is hard on the body. Third, if the momma cat is in poor physical health or not fed a high enough fat and protein diet while pregnant she may have aborted the kitten to save her own body. Pregnant queens need a high quality meat first diet. Fourth, if mom had a disease she could abort the kittens. Fifth, it could have been stress induced if there was a significant change in environment or something. If this was her first litter and she was young it is more likely that it will only be a one time thing that she delivers dead kittens. If this is not a pure-bred breeding cat I would recommend spaying her anyhow because the world doesn’t need more cats, and having miscarriages is stressful and potentially dangerous
