description: A code classifying the person's sex assigned at birth  as specified by the [Office of the National Coordinator for Health IT (ONC)](https://www.healthit.gov/newsroom/about-onc). This extension aligns with the C-CDA Birth Sex Observation (LOINC 76689-9). This extension is no longer a *USCDI Requirement* with the introduction of the US Core Sex Extension in version 6.1.0.
package_name: hl7.fhir.us.core
derivation: constraint
name: USCoreBirthSexExtension
type: Extension
elements:
  url:
    pattern: {type: Uri, value: 'http://hl7.org/fhir/us/core/StructureDefinition/us-core-birthsex'}
    index: 0
  value:
    choices: [valueCode]
    index: 2
  valueCode: {type: code, choiceOf: value, index: 3}
package_version: 6.1.0-snapshot1
class: extension
kind: complex-type
url: http://hl7.org/fhir/us/core/StructureDefinition/us-core-birthsex
base: http://hl7.org/fhir/StructureDefinition/Extension
version: 6.1.0-snapshot1
required: [valueCode, value]