A small baby can't take care of himself, itself, or oneself. I quote this from our school test paper. Which reflexive pronoun is correct? As you do not have the option of choosing 'him/herself', you'd need to pick 'itself'.
What is the reflexive pronoun of doctor, teacher, engineer?
You'll find the following interesting (it's from the WordReference dictionary):
▶pronoun [third person sing.]
informal - used instead of ‘himself’ or ‘herself’ to refer to a person of unspecified sex.
usage: The standard reflexive form corresponding to they and them is themselves. The singular form themself has been used recently to correspond to the singular use of they when referring to a person of unspecified sex, as in helping someone to help themself. However, themself is not regarded as good English, and themselves should be used instead.