The phrase "angel baby" is used to refer to a person, usually a child, who is very innocent, pure, or beautiful, like an angel. It's a term of endearment to express how special someone is. Full definition
What a wonderful way to reflect on the gifts from your sweet angel baby and help others who walk the miscarriage path. (momentsaday.com)
For a time, she felt left out without a special name; babies that die are sometimes called angel babies, and the children born after loss are called rainbow babies. (pregnancyafterlosssupport.com)