Apple Watch Series 8 uses the temperature sensor to provide women with retrospective ovulation estimates, which can be helpful for family planning purposes. The data also provides improved period predictions, and in watchOS 9, women can receive notifications if a logged cycle history shows a possible deviation like irregular, infrequent, or prolonged periods.

The watch uses an OLED ultra low power temperature poly-silicon and oxide display (LTPO) to enable Always-On functionality, which allows the watch face, complications, and other information to be continually visible.




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