We get a lot of questions about how many green days to expect in the beginning when using NaturalCycles, since NaturalCycles needs some data to get to know you and your body. Every woman is different, with different cycle characteristics and different body temperatures, so we cannot make any reliable assumptions about your body until you start entering your own data in your NaturalCycles account.
The number of green days a woman gets in the first ovulatory cycle depends a lot on those first data points. What cycle day did she start measuring at? Does she measure every day or does she skip a lot of days? How much is her temperature fluctuating? Which cycle day does she ovulate? Has she recently been on hormonal contraception and will this postpone ovulation? I’ve already written a separate blog entry concerning how much the pill affects your cycle, here:
NaturalCycles requires 6 low temperature values before looking for a rise due to ovulation. This means that if she ovulates around day 15, she needs to start measuring around day 10 at the latest. If she starts measuring after the temperature rise, then it is of course not possible for NaturalCycles to detect ovulation. Below is such an example, where she started measuring on day 21:
One could argue that most probably ovulation had happened there and NaturalCycles could give green days, but before the following menstruation, there is really no way of knowing whether ovulation has happened and if the temperature is high, or if ovulation is for some reason delayed and the rise is still to come. As safety comes first, these days should not be green!
Below you see another example of a user that started measuring her temperature on cycle day 11, ovulated on day 20 and then got green days on day 23. She also entered a first positive LH test (ovulation test) on day 20, which helps to get easier green days.
In some extreme scenarios, where the woman does not measure very often in combination with highly fluctuating temperatures, it can take up to two cycles to get the first post-ovulatory green days.
To summarize: on average, if a user starts measuring before ovulation, she gets 40.2% green days during her first cycle. So even though the number of green days in the first cycle varies greatly, depending on several factors, the users do on average get a significant amount of green days.