There are unique consent requirements —as well as some other special regulatory requirements — for research that involves certain vulnerable populations:
Children and minors: Federal regulations include requirements for parental permission (consent) and assent from children.
Pregnant women, fetuses, neonates or human in vitro fertilization: Consent may be required from only the woman or the woman and the father. See the guidance page for specific requirements, as well as info to include in the consent form.
Prisoners: There are a number of restrictions on research involving prisoners, and these studies require extra review time.