Several indicators can determine a woman's fertility status and where she is in her cycle due to the hormones that are released during the menstrual cycle. Natural Cycles uses basal body temperature (BBT), and LH measurements as these indicators are the most scientifically accurate and objective measurements as well as being the easiest to track.
Basal body temperature (BBT)
BBT is your resting body temperature. A rise in BBT (about 0.3°C or 0.5°F) coincides with an increase in the hormone progesterone. This occurs once a woman has ovulated and has entered the luteal phase - the infertile stage of the cycle. You can read more about your basal body temperature here.
Luteinizing Hormone (LH) tests (optional), also known as ovulation tests, measure the amount of LH in a woman's urine. LH levels rise roughly 48h before ovulation and initiate ovulation. A positive result on an LH test, followed by elevated temperatures, confirms that ovulation has occurred.
Quantitative indicators reduce human error
Natural Cycles is a simple and user-friendly method of contraception. This means we have decided to solely include BBT and LH as data entry points to confirm ovulation. The app's intelligent algorithm takes a woman's menstrual cycle patterns and monthly variations into consideration, including a woman's cycle history, cycle irregularity, temperature fluctuations, the recent usage of hormonal contraception, ovulation day variation, sperm survival.
You are now able to track cervical mucus in the app. While cervical mucus can be a fertility indicator, our algorithm doesn't take it into account when calculating your fertility. Your temperature is the main indicator for detecting ovulation. However, tracking cervical mucus in the app is an excellent way to learn more about your unique cycle. You can read more about this here.
If you would like to track other fertility indicators, you can add them to the "Notes" section of your Add Data page.