Columbia subject headings:
Adoption.
Childlessness.
Foster parents.
Parenthood.
Stepparents.
Surrogate mothers.
Harvard subject headings:
Adoption.
Childlessness.
Foster parents.
Parenthood.
Stepparents.
Surrogate mothers.
Princeton subject headings:
Adoption.
Childlessness.
Foster parents.
Parenthood.
Stepparents.
Surrogate mothers.