The phrase "helpless infant" refers to a very young baby who cannot do things for themselves and needs assistance from others to meet their basic needs. Full definition
My wife and I were now the proud parents of a little helpless infant. (inc.com)
The opportunity to see a little life blossom from a totally helpless infant into a growing kitten with its own personality is like no other. (southjerseyregionalanimalshelter.org)
«The changes could confer an advantage for the mother by strengthening her ability to read the needs of her relatively helpless infant,» says Hoekzema. (newscientist.com)