5 dead babies after birth

Question
My guinea pig Cilia just gave birth this morning to five babies, the problem is, they are all dead.  We have been feeling those babies kick for weeks now, and have had much joy in doing so. Even yesterday, there was nothing abnormal, they were kicking and the mother was happy. And then today she has them, all dead. I saw her birth the last baby, and it was still born. she had successfully cleaned three of her first ones, but then one she hadn't. I don't know if it's normal or not, but it had this shade of yellow all over its sack, I don't know if it had died in her and become poisonous? Tho it was just yesterday they were alive. Just in a bit of confusion as to why they all died just before birth or during. And just some info on the mother, she is very thin as to having lots of babies, thats normal for our guinea pigs and they gain their weight back nicely every time, but she was stressed a little during her pregnancy, and started pulling out her hair. I had another guinea pig do this when she was pregnant, and she had 2 babies, one was dead. Hope this helps.
Thank you for your time,
Madeleine

Answer
sometimes they just die, it is horrible but you can't really do anything about it and sadly we don't always know why this happens, stress can be a cause, but then sometimes they deliver fine when stressed and other times they die when there was nothing to complicate anything.