Natural Cycles and other contraceptive options


The information and questions provided below are designed to support your counseling so that you and your patients can make informed choices.

Who is Natural Cycles suitable for?/Who is Natural Cycles less suitable for?

Please see our webpage The right patient.

Getting your patient started on Natural Cycles

Once you and your patient have decided that Natural Cycles is the right contraceptive option, they will need to go through the following steps:


A user can access Natural Cycles via their web browser: and download the Natural Cycles app through the App Store or through Google Play. They then complete the sign-up for a monthly or an annual subscription, or test the app for free before signing up.


If they do not have a Natural Cycles basal thermometer (it’s included in the annual subscription), one can be ordered from our webshop, or purchased from the nearest pharmacy.


After signing up, the user takes their temperature with a basal thermometer first thing in the morning (when body temperature is at its lowest) before getting up and out of bed. The reading is then entered into the app. That data builds into a personalised fertility indicator that informs her when she needs to use protection, or time intercourse to minimise or maximise the chance of conception.


An optional feature is LH testing (an ovulation test) with urine test strips a few times per cycle, on the days leading up to her expected ovulation. Ovulation tests are particularly recommended if she is planning a pregnancy, since these help pinpoint her most fertile days.

Aspects to consider before recommending Natural Cycles

More red days in the beginning

The algorithm adapts to every woman’s unique cycle pattern by learning over time as she adds more data. The number of green days increases accordingly, therefore, a woman who inputs temperature readings regularly and often (at least 5 times a week), has a regular cycle and a non-deviating temperature is likely to receive more green days. The algorithm has been intricately designed to account for sperm survival, variation in cycle length, ovulation day, temperature fluctuations and the length of the follicular and luteal phase, and is sensitive to subtle patterns in a woman’s cycle.

In light of this information, it is necessary to inform patients that patience is required over the first few weeks, and that it may take several cycles of consistent measuring and entering data for the app to become familiar with a woman’s individual cycle and detect ovulation. As such, it is normal that more red days are given initially.

  • Having recently stopped hormonal contraception
  • Highly irregular cycles
  • Atypical fluctuating temperatures

Women discontinuing hormonal contraception

For women who have recently stopped using hormonal contraception, it is not unusual to experience anovulatory cycles for a couple of months.

A woman can start using Natural Cycles the day after she discontinues using hormonal contraception. Until her first ovulation is detected, she should expect many red days as a Prevent user.

IMPORTANT: women should not measure while still on hormonal contraception since the hormones inhibit ovulation and also affect temperature and cycles. Therefore a combination of hormonal contraception and Natural Cycles is not possible.

Women with irregular cycles

Small irregularities are quite common, especially if a woman has recently stopped using hormonal contraception. The Natural Cycles algorithm takes factors such as cycle regularity and temperature fluctuations into account when analysing individual cycles and calculating fertility status for the day.

Natural Cycles may be less suitable as a contraceptive if a woman’s cycle is very irregular, since she will get more red days, yet by tracking her cycle, she will get to know how her own individual cycle.

1Berglund Scherwitzl E, Lindén Hirschberg A, Scherwitzl R. Identification and prediction of the fertile window using NaturalCycles. The European Journal of Contraception & Reproductive Health Care. 2015;20(5):403-408.
Contraceptive Method% of women experiencing
an unintended pregnancy
within the first year of use
Protection against
User-dependentPotential non-
Potential side effects
Natural Cycles¹7NoYesYes⁴No
Copper IUD²0.8NoNoNoYes⁵
Hormonal IUS²0.2NoNoYesYes, hormone-related
Traditional³ fertility
Male condom²18YesYesNoNo
Combined pill and
progestin-only pill²
9NoYesYesYes, hormone-related

¹Berglund Scherwitzl E, Lundberg O, Kopp Kallner H, Gemzell Danielsson K, Trussell J, Scherwitzl R. Perfect-use and typical-use Pearl Index of a contraceptive mobile app. Contraception. 2017;96(6):420-425.
²Trussell J. Contraceptive failure in the United States. Contraception. 2011;83(5):397-404
³Non-digital, without the help of a personalised algorithm
4Hatcher R. Contraceptive technology. 20th ed. [New York, N.Y.]: Ardent Media; 2011.
5E.g. Cramps, pelvic infections, heavier periods, ectopic pregnancies

Natural Cycles’ effectiveness is based on clinical research, please see the results of our clinical studies and peer-reviewed publications.