Gender fluid is a term used to describe a person whose gender identity can change or shift over time. This may involve feeling more masculine, feminine, or somewhere in between at different points. It reflects a fluidity and variability in how one experiences and expresses their gender.

Gender fluidity in children is only in the early stages of study. No results are known as of 2017.

Gender identity is a person's internal sense of their own gender, which may not necessarily align with the sex they were assigned at birth. It is a deeply-held understanding of oneself as male, female, a blend of both, or neither. Gender identity can be fluid and may change over time.

In traditional folklore and fantasy literature, elves are typically depicted as androgynous or having fluid gender identities. They are often portrayed as being able to change their physical appearance to match their gender expression or societal role.

Either by having an ultrasound scan, or by having the amniotic fluid tested.