Intersex people are born with atypical physical sex characteristics that can complicate initial sex assignment and lead to involuntary or coerced medical treatment.   The term cisgender "can get confusing" in relation to people with intersex conditions, according to the Advocates for Informed Choice Inter/Act project.  Hida Viloria of OII-USA notes that, as a person born with an intersex body who has a non-binary sense of gender identity that "matches" his/her body, s/he is both cisgender and gender non-conforming, presumably opposites according to cisgender's definition, and that this evidences the term's basis on a binary sex model that does not account for intersex people's existence. S/he also critiques the fact that the term "sex assigned at birth" is used in one of cisgender's definitions without noting that babies are assigned male or female regardless of intersex status in most of the world, stating that doing so obfuscates the birth of intersex babies and frames gender identity within a binary male/female sex model that fails to account for both the existence of natally congruent gender non-conforming gender identities, and gender-based discrimination against intersex people based on natal sex characteristics rather than on gender identity or expression, such as "normalizing" infant genital surgeries.  Organisation Intersex International Australia argues that, while most intersex people are not transgender, the term is problematic because of intersex people's experience, or risk of experiencing, "involuntary medical treatment to impose stereotypical sex characteristics".  Intersex professor Cary Gabriel Costello has proposed using the term "ipso gender" instead of cisgender for intersex people who agree with their birth sex designation.