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Natural Cycles is a mobile app designed to help women track their fertility. The app predicts the days on which a woman is fertile and may be used for planning pregnancy and contraception. It was developed by CERN scientist Elina Berglund, who founded the company with her husband, Raoul Scherwitzl.[1][2][3][4]

The app was the first to be certified as a contraceptive in the European Union and in August 2018 the Food and Drug Administration approved U.S. marketing for the app.[5]

The app has come under criticism for misleading advertising and potential lack of efficacy.



Dr. Berglund was a physicist at CERN who was part of the Higgs boson discovery, before co-founding the company with her husband Dr. Scherwitzl. Because the couple was in search of an alternative natural contraceptive themselves, Berglund used data analysis to develop an algorithm designed to pinpoint her ovulation.

The couple then decided to create an app with the underlying algorithm, Natural Cycles. Following several medical trials, the app became the first tech-based device to be certified for use as contraception in the European Union in February 2017 by the European inspection and certification organisation TÜV SÜD.[4] In November 2017 Natural Cycles received a $30M investment in series B round led by EQT Ventures fund, with participation from existing investors Sunstone, E-ventures and Bonnier Growth Media (the VC arm of privately held Swedish media group, the Bonnier Group).[6]

While the app is currently only certified in the European Union, where its users are concentrated in the United Kingdom and the Scandinavian countries, it is available worldwide. Natural Cycles offers a subscription product, which had over 800,000 users across 160 countries as of June 2018. 75 percent use the app as a contraceptive, and the rest use it to try and become pregnant.[7]

The app works by taking your temperature each morning, under the tongue as soon as you wake up in the morning and logging it into the app. This is done with a basal thermometer. The apps algorithm calculation is based on the observation that post-ovulation, progesterone warms the female body by up to 0.45C.[8] Natural Cycles algorithm then determines, based on the temperature, whether the user is fertile or not. A red day means fertile (which is when you should abstain or use a condom), a green day means not fertile.[9] For the app to remain effective, women need to follow the app's instructions correctly, and it does not protect its users from sexually transmitted diseases.[4]

In 2019, the company completed a pilot program in Sweden that tested a feature to help women trying to get pregnant determine if they should seek fertility help.[10] A new mode also became available in 2019 that helps users monitor pregnancy.[10]


Studies carried out by the app's creators have found it to be as effective in preventing pregnancies as the contraceptive pill.[1][11] These studies, however, only consider women who used the app in a "perfect use" scenario - the rate of pregnancies was higher when considering all users - and only considered users who were paying members and were within the age range 20-35.[12][13]


In 2018, Södersjukhuset, a hospital in Stockholm, Sweden filed a complaint with the Medical Products Agency of Sweden after 37 women who had been using Natural Cycles as their primary method of contraception sought an abortion at the hospital after becoming pregnant unintentionally.[14] Natural Cycles responded by saying the number of pregnancies was within the reported effectiveness rates.[15][16] In the UK, the app came under investigation by the Advertising Standards Authority over supposedly misleading claims in its marketing; the complaint was upheld by the ASA in August 2018, concluding that the app misled consumers regarding being "highly accurate" and a "clinically tested alternative to birth control".[17] A number of users and healthcare professionals have expressed concerns over the efficacy of the app.[18]

In August 2018, Lauren Streicher, professor of clinical obstetrics at Northwestern University's Feinberg School of Medicine expressed concerns over the Food and Drug Administration's approval of the app. Streicher has claimed that the app is "problematic" as it relies on users' self-reported temperatures which must be taken as soon as they wake up each morning in order to be accurate. In an interview with Vox, Streicher claimed "The minute you rely on action, the efficacy goes down.”[19]

Natural Cycles has also been criticised for its marketing strategy of paying social media influencers to promote the app. In July 2018 researchers at the London School of Hygiene and Tropical Medicine published a study which claimed “Natural Cycles’ marketing materials ought to be entirely transparent, more clear than they currently are about the limitations of their app and pregnancy risks”[12][19]

See alsoEdit


  1. ^ a b Emma Lundin (7 November 2016), "Could an algorithm replace the pill?", The Guardian
  2. ^ Daniela Walker (4 October 2016), "Can an algorithm replace the pill?", Wired
  3. ^ Claire Cohen (20 June 2015), "Could an app replace the contraceptive pill?", Daily Telegraph
  4. ^ a b c Maddy Savage (7 August 2017). "The Swedish physicist revolutionising birth control". BBC news.
  5. ^ Thorbecke, Catherine (August 12, 2018). "FDA approves marketing for a contraception app for the 1st time". ABC News. Retrieved August 13, 2018.
  6. ^ Lomas, Natasha. "Natural Cycles gets $30M for its EU-certified "digital contraception"". TechCrunch. Retrieved 2017-12-15.
  7. ^ "A Swedish app that wants to replace your birth control pill has raised $30 million to expand to the US". Business Insider. Retrieved 2017-12-15.
  8. ^ Cohen, Claire (2016-04-13). "Could an app really replace the contraceptive pill?". The Telegraph. ISSN 0307-1235. Retrieved 2017-12-15.
  9. ^ "P-piller i appform – varför satsar någon pengar på det?". Breakit (in Swedish). Retrieved 2017-12-15.
  10. ^ a b "It's Tough Being the First Birth Control App". 2019-04-01. Retrieved 2019-06-12.
  11. ^ Berglund Scherwitzl E, Lundberg O, Kopp Kallner H, Gemzell Danielsson K, Trussell J, Scherwitzl R (December 2017). "Perfect-use and typical-use Pearl Index of a contraceptive mobile app". Contraception. 96 (6): 420–425. doi:10.1016/j.contraception.2017.08.014. PMC 5669828. PMID 28882680.
  12. ^ a b Hough, Amy; Bryce, Maggie; Forrest, Simon (2018-07-21). "Social media and advertising natural contraception to young women: the case for clarity and transparency with reference to the example of 'Natural Cycles'". BMJ Sex Reprod Health: bmjsrh–2018–200110. doi:10.1136/bmjsrh-2018-200110. ISSN 2515-1991.
  13. ^ "Would you trust a smartphone app as a contraceptive?". NHS. 15 April 2016. Retrieved 10 February 2019.
  14. ^ "Hyped birth control app Natural Cycles has been reported to the authorities - after 37 unwanted pregnancies". Retrieved 2018-08-14.
  15. ^
  16. ^
  17. ^ "Contraceptive app investigated over 'misleading' claims about its accuracy". The Independent. Retrieved 2018-08-14.
  18. ^ Sudjic, Olivia (2018-07-21). "'I felt colossally naive': the backlash against the birth control app". the Guardian. Retrieved 2018-08-14.
  19. ^ a b "The first "birth control app" was just approved by the FDA. Its transparency and effectiveness are in question". Vox. Retrieved 2018-08-14.