Natural Cycles is a digital birth control/contraception. Cleared by FDA in the US, CE marked in Europe.
Based on an intelligent algorithm, Natural Cycles analyzes a woman's basal body temperature (BBT) and Luteinizing Hormone (LH) data to identify her fertile and non-fertile days.
By measuring and adding the basal temperature in the morning (5 values per week is recommended), the algorithm gets to know the woman and her unique menstrual cycle. After 1-3 cycles of measuring, the algorithm has gotten to know her well enough to be able to confirm when ovulation has occurred.
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The key is to know when a woman ovulates.
Ovulation is the day a woman can get pregnant as it is the phase of the menstrual cycle when an egg is released from the ovaries and can be fertilized by sperm. Since sperm can survive up to 5 days in the female body, a woman is only fertile for ~6 days per cycle.
The algorithm then gives out red or green days according to fertility status for the day.
- Red days: You are fertile and should use protection during intercourse.
- Green day: You are not fertile and do not need to use protection during intercourse.
Natural Cycles uses two well-known indicators of ovulation to confirm it has occurred:
a) Basal Body Temperature (BBT)
- A rise in temperature (0.2-0.45C) is observed after ovulation, as the progesterone is released.
b) Luteinizing Hormone (LH)
- A surge in LH hormones occurs two days before ovulation and marks the most fertile days.
Natural Cycles uses temperature as the primary indicator and recommends using LH tests to detect and confirm ovulation quickly. We see that Natural Cycles Prevent users who add positive LH tests get roughly 5% more green days per cycle. For users who Plan a pregnancy, it helps the algorithm narrow down the most fertile days.
What about irregular cycles?
No worries there, thanks to all the data that you add into the app, Natural Cycles will get to know you and your unique cycle and will adapt accordingly. Cyclers with irregular cycles may experience more red days, but the effectiveness of the algorithm is the same.
In the picture above, you can see the temperature throughout the cycle, and the increase in temperature that occurs after ovulation. You can also see the hormone levels throughout the cycle, and how it affects the basal temperature.