There is No Expiation Upon Her

A woman was breast feeding her child in the bed. She then left that child to look after other children. She stayed with the other children until they slept. She also was exhausted and slept with them. When she woke, she found that the first baby cried a great deal and was being affected by the crying. He was taken to the hospital and stayed there a number of days. He then died because of that. The question is: Does that mother have to make an expiation? If so, what is it?