Assigned Sex at Birth

Assigned sex at birth, also birth sex, natal sex, biological sex, or sex: Assigned sex at birth is a multidimensional biological construct that describes an individual’s reproductive, hormonal, anatomical, and genetic characteristics — or “sex traits.” Biological sex is male, female, or intersex—showing variations in how sex traits are expressed. Health workers delivering a baby will assign a male or female label based on external anatomy — also used on birth certificates. The gender binary options — biological male or female — might not describe the complex biological, anatomical, and chromosomal variations that can occur inside a person’s body, nor necessarily align with how a person’s feels or identifies later on. Specific terms are assigned male at birth (AMAB) and assigned female at birth (AFAB). Most people are labeled male or female, and this is what’s put on their birth certificates.