Represents the gestational age of the current pregnancy, expressed as a time duration (typically completed weeks and/or days).

Gestational age is the age (duration) of a pregnancy, usually measured from the first day of the pregnant person's last menstrual period (LMP) and expressed in completed weeks and/or days. It is a key clinical parameter for dating a pregnancy, assessing fetal growth, and interpreting imaging findings during the antenatal period.

This profile is aligned with the equivalent European Patient Summary (EPS) profile. See the current build version of the EPS profile: Observation: Pregnancy - Gestational Age (EPS).

Tracked by FHIR-56316: once this ticket is resolved, this profile must be aligned with the EU core profile. If the overlap is complete, it will be removed from this specification and the specification will refer to the EU core definition instead.

• Key Elements Table
• Differential Table
• Snapshot Table
• Statistics/References
• All

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7, obs-8
Observation.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Observation.contained		0..*	Resource	Contained, inline Resources
Observation.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored
Observation.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	registered | preliminary | final | amended + Binding: ObservationStatus (required): Codes providing the status of an observation.
Observation.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.value[x]	Σ This element is included in summaries. C	1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Observation.status	Base	required	Observation Status	📍5.0.0	FHIR Std.
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Observation	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Observation	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().ofType(canonical) | %resource.descendants().ofType(uri) | %resource.descendants().ofType(url))) or descendants().where(reference = '#').exists() or descendants().where(ofType(canonical) = '#').exists() or descendants().where(ofType(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Observation	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Observation	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Observation	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
obs-6	error	Observation	dataAbsentReason SHALL only be present if Observation.value[x] is not present	dataAbsentReason.empty() or value.empty()
obs-7	error	Observation	If Observation.component.code is the same as Observation.code, then Observation.value SHALL NOT be present (the Observation.component.value[x] holds the value).	value.empty() or component.code.where(coding.intersect(%resource.code.coding).exists()).empty()
obs-8	error	Observation	bodyStructure SHALL only be present if Observation.bodySite is not present	bodySite.exists() implies bodyStructure.empty()

This structure is derived from Observation

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation		0..*	Observation	Measurements and simple assertions
Observation.code		1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.value[x]		1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Documentation for this format

Terminology Bindings (Differential)

Path	Status	Usage	ValueSet	Version	Source
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7, obs-8
Observation.id	Σ This element is included in summaries.	0..1	id	Logical id of this artifact
Observation.meta	Σ This element is included in summaries.	0..1	Meta	Metadata about the resource
Observation.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Observation.language		0..1	code	Language of the resource content Binding: AllLanguages (required): IETF language tag for a human language Additional Bindings Purpose CommonLanguages Starter
Observation.text		0..1	Narrative	Text summary of the resource, for human interpretation This profile does not constrain the narrative in regard to content, language, or traceability to data elements
Observation.contained		0..*	Resource	Contained, inline Resources
Observation.extension		0..*	Extension	Additional content defined by implementations
Observation.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored
Observation.identifier	Σ This element is included in summaries.	0..*	Identifier	Business Identifier for observation
Observation.instantiates[x]	Σ This element is included in summaries.	0..1	canonical(ObservationDefinition), Reference(ObservationDefinition)	Instantiates FHIR ObservationDefinition
Observation.basedOn	Σ This element is included in summaries.	0..*	Reference(CarePlan | DeviceRequest | ImmunizationRecommendation | MedicationRequest | NutritionOrder | ServiceRequest)	Fulfills plan, proposal or order
Observation.triggeredBy		0..*	BackboneElement	Triggering observation(s)
Observation.triggeredBy.id		0..1	string	Unique id for inter-element referencing
Observation.triggeredBy.extension		0..*	Extension	Additional content defined by implementations
Observation.triggeredBy.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.triggeredBy.observation	Σ This element is included in summaries.	1..1	Reference(Observation)	Triggering observation
Observation.triggeredBy.type	Σ This element is included in summaries.	1..1	code	reflex | repeat | re-run Binding: TriggeredBytype (required): The type of TriggeredBy Observation.
Observation.triggeredBy.reason		0..1	string	Reason that the observation was triggered
Observation.partOf	Σ This element is included in summaries.	0..*	Reference(MedicationAdministration | MedicationDispense | MedicationStatement | Procedure | Immunization | ImagingStudy | GenomicStudy)	Part of referenced event
Observation.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	registered | preliminary | final | amended + Binding: ObservationStatus (required): Codes providing the status of an observation.
Observation.category		0..*	CodeableConcept	Classification of type of observation Binding: ObservationCategoryCodes (preferred): Codes for high level observation categories.
Observation.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.subject	Σ This element is included in summaries.	0..1	Reference(Patient | Group | Device | Location | Organization | Procedure | Practitioner | Medication | Substance | BiologicallyDerivedProduct | NutritionProduct)	Who and/or what the observation is about
Observation.focus	Σ This element is included in summaries.	0..*	Reference(Resource)	What the observation is about, when it is not about the subject of record
Observation.encounter	Σ This element is included in summaries.	0..1	Reference(Encounter)	Healthcare event during which this observation is made
Observation.effective[x]	Σ This element is included in summaries.	0..1		Clinically relevant time/time-period for observation
Observation.effective[x].effectiveDateTime			dateTime
Observation.effective[x].effectivePeriod			Period
Observation.effective[x].effectiveTiming			Timing
Observation.effective[x].effectiveInstant			instant
Observation.issued	Σ This element is included in summaries.	0..1	instant	Date/Time this version was made available
Observation.performer	Σ This element is included in summaries.	0..*	Reference(Practitioner | PractitionerRole | Organization | CareTeam | Patient | RelatedPerson)	Who is responsible for the observation
Observation.value[x]	Σ This element is included in summaries. C	1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Observation.dataAbsentReason	C	0..1	CodeableConcept	Why the result is missing Binding: DataAbsentReason (extensible): Codes specifying why the result (Observation.value[x]) is missing.
Observation.interpretation		0..*	CodeableConcept	High, low, normal, etc Binding: ObservationInterpretationCodes (extensible): Codes identifying interpretations of observations.
Observation.note		0..*	Annotation	Comments about the observation
Observation.bodySite	C	0..1	CodeableConcept	Observed body part Binding: SNOMEDCTBodyStructures (example): SNOMED CT Body site concepts
Observation.bodyStructure	C	0..1	Reference(BodyStructure)	Observed body structure
Observation.method		0..1	CodeableConcept	How it was done Binding: ObservationMethods (example): Methods for simple observations.
Observation.specimen	C	0..1	Reference(Specimen | Group)	Specimen used for this observation Constraints: obs-9
Observation.device		0..1	Reference(Device | DeviceMetric)	A reference to the device that generates the measurements or the device settings for the device
Observation.referenceRange	C	0..*	BackboneElement	Provides guide for interpretation Constraints: obs-3
Observation.referenceRange.id		0..1	string	Unique id for inter-element referencing
Observation.referenceRange.extension		0..*	Extension	Additional content defined by implementations
Observation.referenceRange.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.referenceRange.low	C	0..1	SimpleQuantity(5.0.0)	Low Range, if relevant Constraints: sqty-1
Observation.referenceRange.high	C	0..1	SimpleQuantity(5.0.0)	High Range, if relevant Constraints: sqty-1
Observation.referenceRange.normalValue		0..1	CodeableConcept	Normal value, if relevant Binding: ObservationReferenceRangeNormalValueCodes (extensible): Codes identifying the normal value of the observation.
Observation.referenceRange.type		0..1	CodeableConcept	Reference range qualifier Binding: ObservationReferenceRangeMeaningCodes (preferred): Code for the meaning of a reference range.
Observation.referenceRange.appliesTo		0..*	CodeableConcept	Reference range population Binding: ObservationReferenceRangeAppliesToCodes (example): Codes identifying the population the reference range applies to.
Observation.referenceRange.age		0..1	Range	Applicable age range, if relevant
Observation.referenceRange.text	C	0..1	markdown	Text based reference range in an observation
Observation.hasMember	Σ This element is included in summaries.	0..*	Reference(Observation | QuestionnaireResponse | MolecularSequence)	Related resource that belongs to the Observation group
Observation.derivedFrom	Σ This element is included in summaries.	0..*	Reference(DocumentReference | ImagingStudy | ImagingSelection | QuestionnaireResponse | Observation | MolecularSequence | GenomicStudy)	Related resource from which the observation is made
Observation.component	Σ This element is included in summaries. C	0..*	BackboneElement	Component results
Observation.component.id		0..1	string	Unique id for inter-element referencing
Observation.component.extension		0..*	Extension	Additional content defined by implementations
Observation.component.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.component.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of component observation (code / type) Binding: LOINCCodes (example): Codes identifying names of simple observations.
Observation.component.value[x]	Σ This element is included in summaries.	0..1		Actual component result
Observation.component.value[x].valueQuantity			Quantity
Observation.component.value[x].valueCodeableConcept			CodeableConcept
Observation.component.value[x].valueString			string
Observation.component.value[x].valueBoolean			boolean
Observation.component.value[x].valueInteger			integer
Observation.component.value[x].valueRange			Range
Observation.component.value[x].valueRatio			Ratio
Observation.component.value[x].valueSampledData			SampledData
Observation.component.value[x].valueTime			time
Observation.component.value[x].valueDateTime			dateTime
Observation.component.value[x].valuePeriod			Period
Observation.component.value[x].valueAttachment			Attachment
Observation.component.value[x].valueReference			Reference(MolecularSequence)
Observation.component.dataAbsentReason		0..1	CodeableConcept	Why the component result is missing Binding: DataAbsentReason (extensible): Codes specifying why the result (Observation.value[x]) is missing.
Observation.component.interpretation		0..*	CodeableConcept	High, low, normal, etc Binding: ObservationInterpretationCodes (extensible): Codes identifying interpretations of observations.
Observation.component.referenceRange		0..*	See referenceRange (Observation)	Provides guide for interpretation of component result
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Observation.language	Base	required	All Languages	📍5.0.0	FHIR Std.
Observation.triggeredBy.​type	Base	required	triggered Bytype	📍5.0.0	FHIR Std.
Observation.status	Base	required	Observation Status	📍5.0.0	FHIR Std.
Observation.category	Base	preferred	Observation Category Codes	📍5.0.0	FHIR Std.
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.
Observation.dataAbsentReason	Base	extensible	Data Absent Reason	📍5.0.0	FHIR Std.
Observation.interpretation	Base	extensible	Observation Interpretation Codes	📍5.0.0	FHIR Std.
Observation.bodySite	Base	example	SNOMED CT Body Structures	📍5.0.0	FHIR Std.
Observation.method	Base	example	Observation Methods	📍5.0.0	FHIR Std.
Observation.referenceRange.​normalValue	Base	extensible	Observation Reference Range Normal Value Codes	📍5.0.0	FHIR Std.
Observation.referenceRange.​type	Base	preferred	Observation Reference Range Meaning Codes	📍5.0.0	FHIR Std.
Observation.referenceRange.​appliesTo	Base	example	Observation Reference Range Applies To Codes	📍5.0.0	FHIR Std.
Observation.component.​code	Base	example	LOINC Codes	📍5.0.0	FHIR Std.
Observation.component.​dataAbsentReason	Base	extensible	Data Absent Reason	📍5.0.0	FHIR Std.
Observation.component.​interpretation	Base	extensible	Observation Interpretation Codes	📍5.0.0	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Observation	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Observation	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().ofType(canonical) | %resource.descendants().ofType(uri) | %resource.descendants().ofType(url))) or descendants().where(reference = '#').exists() or descendants().where(ofType(canonical) = '#').exists() or descendants().where(ofType(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Observation	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Observation	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Observation	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
obs-3	error	Observation.referenceRange	Must have at least a low or a high or text	low.exists() or high.exists() or text.exists()
obs-6	error	Observation	dataAbsentReason SHALL only be present if Observation.value[x] is not present	dataAbsentReason.empty() or value.empty()
obs-7	error	Observation	If Observation.component.code is the same as Observation.code, then Observation.value SHALL NOT be present (the Observation.component.value[x] holds the value).	value.empty() or component.code.where(coding.intersect(%resource.code.coding).exists()).empty()
obs-8	error	Observation	bodyStructure SHALL only be present if Observation.bodySite is not present	bodySite.exists() implies bodyStructure.empty()
obs-9	error	Observation.specimen	If Observation.specimen is a reference to Group, the group can only have specimens	(reference.resolve().exists() and reference.resolve() is Group) implies reference.resolve().member.entity.resolve().all($this is Specimen)
sqty-1	error	Observation.referenceRange.low, Observation.referenceRange.high	The comparator is not used on a SimpleQuantity	comparator.empty()

Key Elements View

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7, obs-8
Observation.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Observation.contained		0..*	Resource	Contained, inline Resources
Observation.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored
Observation.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	registered | preliminary | final | amended + Binding: ObservationStatus (required): Codes providing the status of an observation.
Observation.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.value[x]	Σ This element is included in summaries. C	1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Observation.status	Base	required	Observation Status	📍5.0.0	FHIR Std.
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Observation	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Observation	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().ofType(canonical) | %resource.descendants().ofType(uri) | %resource.descendants().ofType(url))) or descendants().where(reference = '#').exists() or descendants().where(ofType(canonical) = '#').exists() or descendants().where(ofType(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Observation	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Observation	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Observation	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
obs-6	error	Observation	dataAbsentReason SHALL only be present if Observation.value[x] is not present	dataAbsentReason.empty() or value.empty()
obs-7	error	Observation	If Observation.component.code is the same as Observation.code, then Observation.value SHALL NOT be present (the Observation.component.value[x] holds the value).	value.empty() or component.code.where(coding.intersect(%resource.code.coding).exists()).empty()
obs-8	error	Observation	bodyStructure SHALL only be present if Observation.bodySite is not present	bodySite.exists() implies bodyStructure.empty()

Differential View

This structure is derived from Observation

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation		0..*	Observation	Measurements and simple assertions
Observation.code		1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.value[x]		1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Documentation for this format

Terminology Bindings (Differential)

Path	Status	Usage	ValueSet	Version	Source
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.

Snapshot ViewView

Name	Flags	Card.	Type	Description & Constraints    Filter: Bindings Constraints Obligations
Observation	C	0..*	Observation	Measurements and simple assertions Constraints: obs-6, obs-7, obs-8
Observation.id	Σ This element is included in summaries.	0..1	id	Logical id of this artifact
Observation.meta	Σ This element is included in summaries.	0..1	Meta	Metadata about the resource
Observation.implicitRules	?! This element is a modifier element. Σ This element is included in summaries.	0..1	uri	A set of rules under which this content was created
Observation.language		0..1	code	Language of the resource content Binding: AllLanguages (required): IETF language tag for a human language Additional Bindings Purpose CommonLanguages Starter
Observation.text		0..1	Narrative	Text summary of the resource, for human interpretation This profile does not constrain the narrative in regard to content, language, or traceability to data elements
Observation.contained		0..*	Resource	Contained, inline Resources
Observation.extension		0..*	Extension	Additional content defined by implementations
Observation.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored
Observation.identifier	Σ This element is included in summaries.	0..*	Identifier	Business Identifier for observation
Observation.instantiates[x]	Σ This element is included in summaries.	0..1	canonical(ObservationDefinition), Reference(ObservationDefinition)	Instantiates FHIR ObservationDefinition
Observation.basedOn	Σ This element is included in summaries.	0..*	Reference(CarePlan | DeviceRequest | ImmunizationRecommendation | MedicationRequest | NutritionOrder | ServiceRequest)	Fulfills plan, proposal or order
Observation.triggeredBy		0..*	BackboneElement	Triggering observation(s)
Observation.triggeredBy.id		0..1	string	Unique id for inter-element referencing
Observation.triggeredBy.extension		0..*	Extension	Additional content defined by implementations
Observation.triggeredBy.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.triggeredBy.observation	Σ This element is included in summaries.	1..1	Reference(Observation)	Triggering observation
Observation.triggeredBy.type	Σ This element is included in summaries.	1..1	code	reflex | repeat | re-run Binding: TriggeredBytype (required): The type of TriggeredBy Observation.
Observation.triggeredBy.reason		0..1	string	Reason that the observation was triggered
Observation.partOf	Σ This element is included in summaries.	0..*	Reference(MedicationAdministration | MedicationDispense | MedicationStatement | Procedure | Immunization | ImagingStudy | GenomicStudy)	Part of referenced event
Observation.status	?! This element is a modifier element. Σ This element is included in summaries.	1..1	code	registered | preliminary | final | amended + Binding: ObservationStatus (required): Codes providing the status of an observation.
Observation.category		0..*	CodeableConcept	Classification of type of observation Binding: ObservationCategoryCodes (preferred): Codes for high level observation categories.
Observation.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of observation (code / type) Binding: ValueSet: Gestational Age (LOINC) (required)
Observation.subject	Σ This element is included in summaries.	0..1	Reference(Patient | Group | Device | Location | Organization | Procedure | Practitioner | Medication | Substance | BiologicallyDerivedProduct | NutritionProduct)	Who and/or what the observation is about
Observation.focus	Σ This element is included in summaries.	0..*	Reference(Resource)	What the observation is about, when it is not about the subject of record
Observation.encounter	Σ This element is included in summaries.	0..1	Reference(Encounter)	Healthcare event during which this observation is made
Observation.effective[x]	Σ This element is included in summaries.	0..1		Clinically relevant time/time-period for observation
Observation.effective[x].effectiveDateTime			dateTime
Observation.effective[x].effectivePeriod			Period
Observation.effective[x].effectiveTiming			Timing
Observation.effective[x].effectiveInstant			instant
Observation.issued	Σ This element is included in summaries.	0..1	instant	Date/Time this version was made available
Observation.performer	Σ This element is included in summaries.	0..*	Reference(Practitioner | PractitionerRole | Organization | CareTeam | Patient | RelatedPerson)	Who is responsible for the observation
Observation.value[x]	Σ This element is included in summaries. C	1..1	Quantity	The age of the fetus. Binding: CommonUCUMCodesForAge (extensible) Additional Bindings Purpose AllUCUMExpressionForTime Max Binding
Observation.dataAbsentReason	C	0..1	CodeableConcept	Why the result is missing Binding: DataAbsentReason (extensible): Codes specifying why the result (Observation.value[x]) is missing.
Observation.interpretation		0..*	CodeableConcept	High, low, normal, etc Binding: ObservationInterpretationCodes (extensible): Codes identifying interpretations of observations.
Observation.note		0..*	Annotation	Comments about the observation
Observation.bodySite	C	0..1	CodeableConcept	Observed body part Binding: SNOMEDCTBodyStructures (example): SNOMED CT Body site concepts
Observation.bodyStructure	C	0..1	Reference(BodyStructure)	Observed body structure
Observation.method		0..1	CodeableConcept	How it was done Binding: ObservationMethods (example): Methods for simple observations.
Observation.specimen	C	0..1	Reference(Specimen | Group)	Specimen used for this observation Constraints: obs-9
Observation.device		0..1	Reference(Device | DeviceMetric)	A reference to the device that generates the measurements or the device settings for the device
Observation.referenceRange	C	0..*	BackboneElement	Provides guide for interpretation Constraints: obs-3
Observation.referenceRange.id		0..1	string	Unique id for inter-element referencing
Observation.referenceRange.extension		0..*	Extension	Additional content defined by implementations
Observation.referenceRange.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.referenceRange.low	C	0..1	SimpleQuantity(5.0.0)	Low Range, if relevant Constraints: sqty-1
Observation.referenceRange.high	C	0..1	SimpleQuantity(5.0.0)	High Range, if relevant Constraints: sqty-1
Observation.referenceRange.normalValue		0..1	CodeableConcept	Normal value, if relevant Binding: ObservationReferenceRangeNormalValueCodes (extensible): Codes identifying the normal value of the observation.
Observation.referenceRange.type		0..1	CodeableConcept	Reference range qualifier Binding: ObservationReferenceRangeMeaningCodes (preferred): Code for the meaning of a reference range.
Observation.referenceRange.appliesTo		0..*	CodeableConcept	Reference range population Binding: ObservationReferenceRangeAppliesToCodes (example): Codes identifying the population the reference range applies to.
Observation.referenceRange.age		0..1	Range	Applicable age range, if relevant
Observation.referenceRange.text	C	0..1	markdown	Text based reference range in an observation
Observation.hasMember	Σ This element is included in summaries.	0..*	Reference(Observation | QuestionnaireResponse | MolecularSequence)	Related resource that belongs to the Observation group
Observation.derivedFrom	Σ This element is included in summaries.	0..*	Reference(DocumentReference | ImagingStudy | ImagingSelection | QuestionnaireResponse | Observation | MolecularSequence | GenomicStudy)	Related resource from which the observation is made
Observation.component	Σ This element is included in summaries. C	0..*	BackboneElement	Component results
Observation.component.id		0..1	string	Unique id for inter-element referencing
Observation.component.extension		0..*	Extension	Additional content defined by implementations
Observation.component.modifierExtension	?! This element is a modifier element. Σ This element is included in summaries.	0..*	Extension	Extensions that cannot be ignored even if unrecognized
Observation.component.code	Σ This element is included in summaries. C	1..1	CodeableConcept	Type of component observation (code / type) Binding: LOINCCodes (example): Codes identifying names of simple observations.
Observation.component.value[x]	Σ This element is included in summaries.	0..1		Actual component result
Observation.component.value[x].valueQuantity			Quantity
Observation.component.value[x].valueCodeableConcept			CodeableConcept
Observation.component.value[x].valueString			string
Observation.component.value[x].valueBoolean			boolean
Observation.component.value[x].valueInteger			integer
Observation.component.value[x].valueRange			Range
Observation.component.value[x].valueRatio			Ratio
Observation.component.value[x].valueSampledData			SampledData
Observation.component.value[x].valueTime			time
Observation.component.value[x].valueDateTime			dateTime
Observation.component.value[x].valuePeriod			Period
Observation.component.value[x].valueAttachment			Attachment
Observation.component.value[x].valueReference			Reference(MolecularSequence)
Observation.component.dataAbsentReason		0..1	CodeableConcept	Why the component result is missing Binding: DataAbsentReason (extensible): Codes specifying why the result (Observation.value[x]) is missing.
Observation.component.interpretation		0..*	CodeableConcept	High, low, normal, etc Binding: ObservationInterpretationCodes (extensible): Codes identifying interpretations of observations.
Observation.component.referenceRange		0..*	See referenceRange (Observation)	Provides guide for interpretation of component result
Documentation for this format

Terminology Bindings

Path	Status	Usage	ValueSet	Version	Source
Observation.language	Base	required	All Languages	📍5.0.0	FHIR Std.
Observation.triggeredBy.​type	Base	required	triggered Bytype	📍5.0.0	FHIR Std.
Observation.status	Base	required	Observation Status	📍5.0.0	FHIR Std.
Observation.category	Base	preferred	Observation Category Codes	📍5.0.0	FHIR Std.
Observation.code	Base	required	ValueSet: Gestational Age (LOINC)	📦1.0.0-ballot	This IG
Observation.value[x]	Base	extensible	Common UCUM Codes for Age	📦5.0.0	FHIR Std.
Observation.dataAbsentReason	Base	extensible	Data Absent Reason	📍5.0.0	FHIR Std.
Observation.interpretation	Base	extensible	Observation Interpretation Codes	📍5.0.0	FHIR Std.
Observation.bodySite	Base	example	SNOMED CT Body Structures	📍5.0.0	FHIR Std.
Observation.method	Base	example	Observation Methods	📍5.0.0	FHIR Std.
Observation.referenceRange.​normalValue	Base	extensible	Observation Reference Range Normal Value Codes	📍5.0.0	FHIR Std.
Observation.referenceRange.​type	Base	preferred	Observation Reference Range Meaning Codes	📍5.0.0	FHIR Std.
Observation.referenceRange.​appliesTo	Base	example	Observation Reference Range Applies To Codes	📍5.0.0	FHIR Std.
Observation.component.​code	Base	example	LOINC Codes	📍5.0.0	FHIR Std.
Observation.component.​dataAbsentReason	Base	extensible	Data Absent Reason	📍5.0.0	FHIR Std.
Observation.component.​interpretation	Base	extensible	Observation Interpretation Codes	📍5.0.0	FHIR Std.

Constraints

Id	Grade	Path(s)	Description	Expression
dom-2	error	Observation	If the resource is contained in another resource, it SHALL NOT contain nested Resources	contained.contained.empty()
dom-3	error	Observation	If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource	contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().ofType(canonical) | %resource.descendants().ofType(uri) | %resource.descendants().ofType(url))) or descendants().where(reference = '#').exists() or descendants().where(ofType(canonical) = '#').exists() or descendants().where(ofType(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
dom-4	error	Observation	If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated	contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
dom-5	error	Observation	If a resource is contained in another resource, it SHALL NOT have a security label	contained.meta.security.empty()
dom-6	best practice	Observation	A resource should have narrative for robust management	text.`div`.exists()
ele-1	error	**ALL** elements	All FHIR elements must have a @value or children	hasValue() or (children().count() > id.count())
ext-1	error	**ALL** extensions	Must have either extensions or value[x], not both	extension.exists() != value.exists()
obs-3	error	Observation.referenceRange	Must have at least a low or a high or text	low.exists() or high.exists() or text.exists()
obs-6	error	Observation	dataAbsentReason SHALL only be present if Observation.value[x] is not present	dataAbsentReason.empty() or value.empty()
obs-7	error	Observation	If Observation.component.code is the same as Observation.code, then Observation.value SHALL NOT be present (the Observation.component.value[x] holds the value).	value.empty() or component.code.where(coding.intersect(%resource.code.coding).exists()).empty()
obs-8	error	Observation	bodyStructure SHALL only be present if Observation.bodySite is not present	bodySite.exists() implies bodyStructure.empty()
obs-9	error	Observation.specimen	If Observation.specimen is a reference to Group, the group can only have specimens	(reference.resolve().exists() and reference.resolve() is Group) implies reference.resolve().member.entity.resolve().all($this is Specimen)
sqty-1	error	Observation.referenceRange.low, Observation.referenceRange.high	The comparator is not used on a SimpleQuantity	comparator.empty()

This structure is derived from Observation

Summary

Mandatory: 1 element

Maturity: 1