A miracle child was an offspring whose existence was considered a miracle.
Harry Kim's parents Mary and John Kim referred to him as their miracle child, as they had tried to have a baby for years until he came along. In 2373, he shared this with Taymon while visiting Taresia, who affirmed their belief. Kim then added that as a result, he wasc spoiled and sacrificed for, something he never felt he deserved. (VOY: "Favorite Son")