Valley Electronics is a Swiss company that makes fertility tracking devices. Daysy is a handheld thermometer used orally each morning, showing fertile and non fertile days.

How it works

After ovulation, progesterone causes resting body temperature to rise slightly. Daysy measures basal temperature before rising and combines it with menstruation dates and cycle patterns. Its algorithm assigns a green, red or yellow fertility status. The app displays temperature and cycle history.

Key considerations

Temperature changes after ovulation, so predictions depend on the algorithm and personal data. Illness, alcohol, poor sleep, travel, medication and different measurement times can disturb readings and create more uncertain days. Daysy does not protect against sexually transmitted infections. Users relying on it to avoid pregnancy must follow the instructions consistently. It does not diagnose infertility, ovulation disorders or hormonal conditions.