library WHOEncounterElements using FHIR version '4.0.1' include FHIRHelpers version '4.0.1' include WHOConcepts called Concepts include WHOCommon called Common include WHOElements called Elements parameter AsOf Date default Today() parameter EncounterId String define "Pregnant Observation": Elements."Pregnant Observation" O where O . encounter . references( EncounterId ) or O . effective . toInterval() starts same day or after AsOf - 9 months