Mortality Patterns in the Intersex Population

Intersex individuals are born with sex characteristics - such as sexual anatomy, reproductive organs, or hormonal or chromosomal patterns - that do not fit typical binary definitions of male or female bodies. This paper provides the first comprehensive population-level evidence on age-specific mortality and cause of death patterns in the intersex population compared to the endosex (i.e., not intersex) population. The study relies on diagnostic codes in Danish administrative health data to observe intersex traits at the individual level across the entire population, identifying more than 1.2% of the Danish population as intersex. Results reveal higher mortality among intersex males in early life, driven by deaths related to congenital disorders, but deaths in childhood remain rare in absolute numbers among both intersex and endosex individuals. Distinctive mid- to late-life survival patterns emerge whereby intersex males' survival probabilities outpace those of endosex males, instead converging towards that of endosex females. At the same time, the survival probability of intersex females is lower than that of endosex females, converging towards that of endosex males. Whilst substantial heterogeneity exists across intersex subgroups, overall intersex mortality patterns - like intersex sex characteristics - fall in between the typical patterns of males and females.