According to a recent Wall Street Journal report, Apple is working on new health-related features for future Apple Watches, including blood pressure measurement and a thermometer to detect fertility.
Towards a personal health assistant
Blood pressure measurement already exists on other smartwatches, but Apple is not the type to incorporate technology until it is proven and lives up to its high standards. Thus, the version that Apple wishes to offer will not require calibration, unlike what is currently done with the competition. For this, the Apple sensor detects the beating of the heart via the blood flow in the arteries near the watch.
Huge clinical study in progress
The temperature measurement will allow it to detect periods of ovulation, as well as fevers. Researchers have already started to study how smartwatches - Apple Watch included - can help detect infectious diseases through temperature. For its part, Apple is conducting a huge clinical study in women to help it develop reliable health technology.