The menstrual cycle and Natural Cycles

Natural Cycles uses women's unique basal body temperature (BBT) readings and LH test results (optional) to pinpoint where a woman is in her monthly cycle - i.e. time of menstruation, ovulation, when she is likely to be fertile (red days) or not (green days).

Each woman has her own individual menstrual cycle pattern. The cycle length, the day ovulation occurs, the amplitude of the rise in temperature, the base temperature in the pre- and post-ovulatory phases and the overall shape of the temperature evolution throughout the cycle are all parameters that vary from woman to woman.

Natural Cycles accurately captures every woman's unique cycle by taking cycle irregularity, temperature fluctuations, recent usage of hormonal contraception, ovulation day variation, sperm survival and several other important factors into consideration.  

The Menstrual Cycle
Your cycles begins with the first day of menstrual bleeding and takes on average 29 days but as aforementioned, this can vary from woman to woman. 

It consists of three phases:
- The follicular phase - is estrogen-rich and cooler (average temperature for our Cyclers: 36.23) 
- The ovulation day - is the day a woman can get pregnant. Two well-known biological indicators of ovulation is a temperature rise of 0.2-0.45 °C and a rise in luteinizing hormone (LH) roughly 48 hours prior to it. (Average ovulation day for our Cyclers: CD 17)
- The Luteal phase - progesterone dominates and ‘warms’ the body (average temperature for our Cyclers: 36.58)

Natural Cycles offers insights into individual's cycle, so women can gain an overview of the most important statistics to help them manage their own health. This is shown in the tab Statistics in the app, which is updated frequently as you add more data.