1. Because of the lawsuit around the pulse oximeter intellectual property, as other commenters mentioned. 2. That would require more battery life than the Appl

1. Because of the lawsuit around the pulse oximeter intellectual property, as other commenters mentioned. 2. That would require more battery life than the Apple Watch offers. There are third-party options that do constant monitoring that either directly or indirectly support Apple Health. You'll need some additional intelligence, in the form of an app or something, to analyze that data. WatchOS won't do it at present.