What Body Temperature Tells You About Your Cycle
How body temperature helps you understand your cycle
August 04, 2026
Understanding your cycle starts with understanding the signals your body already gives you. One of those signals is temperature, which shifts in small but measurable ways across the menstrual cycle.
WHOOP 5.0 and WHOOP MG can capture skin temperature while you sleep and send that data to Natural Cycles, the first and only FDA-cleared birth control app. Natural Cycles then applies its algorithm to calculate your daily fertility status in the Natural Cycles app.
Natural Cycles is the birth control. WHOOP provides temperature data; WHOOP is not a contraceptive device, and the WHOOP app is not intended for pregnancy prevention or fertility-status display.
Why temperature changes across the cycle
After ovulation, progesterone rises. That hormonal shift causes a small but measurable increase in resting body temperature. When tracked consistently, temperature can help identify patterns across the menstrual cycle. The Natural Cycles algorithm uses temperature and other cycle data to calculate your fertility status directly in the NC° app.
Why consistent measurement matters
Traditional basal body temperature tracking usually requires measuring at the same time every morning, before getting out of bed. That can be difficult to maintain consistently.
Overnight measuring with a compatible WHOOP device removes the manual morning temperature step. You wear WHOOP while you sleep, WHOOP captures skin temperature overnight, and the data syncs to the Natural Cycles app in the morning.
Where Natural Cycles° fits
Natural Cycles is the first FDA-cleared birth control app. It is hormone-free and uses its algorithm to calculate a daily fertility status: a Red Day when you are fertile, or a Green Day when you are not.
Natural Cycles is 98% effective at preventing pregnancy when used as intended and 93% effective with typical use (source). No method of birth control is 100% effective. It also does not protect against sexually transmitted infections.
For contraceptive guidance, eligibility, and daily fertility status, use the Natural Cycles app.
Where WHOOP fits
WHOOP measures skin temperature overnight. When connected to Natural Cycles, WHOOP sends that temperature data to Natural Cycles when you wake up.
The WHOOP app shows sync status only. Your Red Day or Green Day status appears in the Natural Cycles app.
WHOOP members who are new to NC° get one year of Natural Cycles included with their WHOOP membership. For a limited time, Natural Cycles users can claim 50% off a Peak or Life WHOOP membership (device included) via the Shop in the NC° app.
Frequently asked questions
Can WHOOP be used for birth control?
No. WHOOP is not a contraceptive device. Compatible WHOOP devices measure skin temperature and can send that data to Natural Cycles. Natural Cycles is the birth control, and fertility status appears only in the NC° app.
How does temperature relate to the menstrual cycle?
After ovulation, progesterone rises and causes a small increase in resting body temperature. This drops again right before menstruation. Tracking temperature data consistently can help the Natural Cycles algorithm calculate your fertility status and provide insights unique to your cycle.
Do I need to take my temperature every morning if I use WHOOP with Natural Cycles°?
No. A compatible WHOOP device measures skin temperature overnight while you sleep. When connected, WHOOP sends that data to the Natural Cycles app in the morning.
Where do I see my fertility status?
In the Natural Cycles app. The WHOOP app does not show Red Day or Green Day status.
Who is eligible for the free year of Natural Cycles°?
WHOOP members who are new to Natural Cycles are eligible for one year of Natural Cycles included with their WHOOP membership. Existing Natural Cycles subscribers are not eligible.
To see exactly how the connection works, read Use WHOOP temperature data with Natural Cycles birth control. To learn more about Natural Cycles, visit naturalcycles.com.