According to the wall street journal some of the features on apple’s new health focused smartwatches needed to be removed because they were either too complicated, broken or would have required regulatory approval. The Apple Watch was originally supposed to support tracking of blood pressure, heart activity, stress levels and various other functions.
One of the features would have used sensors to detect skin conductivity to monitor both stress levels and heart rate. However this proved to be too big of a challenge since inconsistencies arose from complications like people with hairy arms, dry skin or how tightly the watch was adhered. Detecting blood pressure also turned out to be too difficult to implement in the watch. Furthermore for the watch to support applications that would give medical advice Apple, would have required approval from the FDA which they were not willing to do.
All of these setbacks would have undoubtedly delayed the watches scheduled release in April, competing with LG, Microsoft, Motorola, Sony, and Samsung who already have similar products on the market. Even though these health features will not be supported when the watch comes out, Apple still plans on including them in future models.