menstrualFlow: HealthKit category type
HKCategoryTypeIdentifierMenstrualFlow · read from Apple’s documentation on 2026-10-02
HKCategoryTypeIdentifier.menstrualFlow (Objective-C HKCategoryTypeIdentifierMenstrualFlow) is a HealthKit category type in Apple's "Reproductive Health" group. Apple's abstract: “A category sample type that records menstrual cycles.” Apple's page names HKCategoryValueMenstrualFlow as the enum its sample values come from. It is available from iOS 9.0 and watchOS 2.0.
What Apple says menstrualFlow is
A category sample type that records menstrual cycles.
Apple’s abstract, quoted from its menstrualFlow reference page, read 2026-10-02. Apple’s discussion of the type runs 128 words.
- Swift
HKCategoryTypeIdentifier.menstrualFlow- Objective-C
HKCategoryTypeIdentifierMenstrualFlow- Family
HKCategoryTypeIdentifier- Apple's topic group
- Reproductive Health
- Group page
- Reproductive health
- Apple's reference
- menstrualFlow on developer.apple.com
Availability
The versions Apple’s documentation data gives for menstrualFlow, platform by platform, as read on 2026-10-02.
| Platform | Introduced | Deprecated |
|---|---|---|
| iOS | 9.0 | — |
| iPadOS | 9.0 | — |
| Mac Catalyst | 13.0 | — |
| macOS | 13.0 | — |
| visionOS | 1.0 | — |
| watchOS | 2.0 | — |
The rest of that release: HealthKit Types Introduced in iOS 9.
What a sample holds
Value enum
HKCategoryValueMenstrualFlow — the enum Apple’s page for menstrualFlow names. Every category type’s enum is on the HKCategoryValue reference.
Aggregation style and unit family apply only to quantity types. For a category type the dataset records neither, because the concept does not apply — not because Apple declined to say.
Can apps write menstrualFlow?
Apple’s documentation for menstrualFlow does not state that its samples are read-only. Apple states read-only status only in prose, and its silence is not a statement either way, so this page makes no claim that apps can save it.
On Android Health Connect
No verified Health Connect counterpart. The cross-platform matrix pairs only metrics checked against both Apple’s and Google’s documentation, and menstrualFlow is not among them. A similarly named Health Connect record may exist, but a name match is not a verified mapping.
Metadata keys Apple ties to it
The HKMetadataKey constants whose own Apple text names menstrualFlow, with the sentence that does, from Apple’s metadata-key pages read 2026-10-04.
- HKMetadataKeyMenstrualCycleStartvalue: Boolean
This metadata key is required for menstrualFlow category samples.
Questions
- Which enum decodes menstrualFlow sample values?
- HKCategoryValueMenstrualFlow. Apple's page for menstrualFlow names that enum as the one its sample values come from.
- Which HealthKit metadata keys mention menstrualFlow?
- HKMetadataKeyMenstrualCycleStart. Apple's text for HKMetadataKeyMenstrualCycleStart: "This metadata key is required for menstrualFlow category samples."
- Which iOS version added menstrualFlow?
- iOS 9.0. Apple's availability data for menstrualFlow lists iOS 9.0, iPadOS 9.0, Mac Catalyst 13.0, macOS 13.0, visionOS 1.0 and watchOS 2.0.
Sources checked
- Apple — HKCategoryTypeIdentifier.menstrualFlow · read 2026-10-02
- Apple — HKCategoryTypeIdentifier · read 2026-10-02
- Apple — HKMetadataKeyMenstrualCycleStart · read 2026-10-04
Apple’s abstract and sentences are quoted for identification; the page layout, the capsule and the cross-platform pairing are AIFitnessAPI’s. Generated from Apple’s documentation by scripts/fetch-healthkit-identifiers.mjs, not typed by hand — the same data as the full identifier table.