Validation of Effectiveness on NaturalCycles Users

Recruiting now

Conditions studied: Contraception

In brief

The goal of this observational study is to measure the effectiveness of the Natural Cycles digital birth control application at preventing pregnancy in sexually active women aged 18 to 35 with no known history of infertility. The main questions it aims to answer are: * What is the pregnancy rate of the application over one year, for all users? * What is the pregnancy rate of the application over one year, for users who follow the application's instructions perfectly? Participants will: * Use the Natural Cycles application for birth control for up to one year. * Log information about daily sexual activity in the app. * Complete a questionnaire at the beginning and end of their participation. * Perform urine pregnancy tests (provided by mail) upon entry to the study, at the start of every cycle during the study, and upon exit from the study.

Key facts

Study ID

NCT07566793

Run by

Natural Cycles

People needed

2000

Starts

2026-04-28

Expected to finish

2027-12-01

Last updated by the study team

2026-07-01

Who can join

Age: 18 and older, up to 35. Sex: female. Healthy volunteers: not accepted.

You may qualify if…

• Wants to avoid pregnancy for 13 cycles.
• Is willing to rely solely on Natural Cycles as their sole contraception method for 13 cycles.
• Is not currently using permanent contraceptive methods, such as sterilization (of either the user or their partner), or hormonal methods, such as the hormonal contraceptive implant or IUD.
• Has an intact uterus, both ovaries and both fallopian tubes to the best of their knowledge.
• Has an average cycle length between 21 and 35 days. The user anticipates heterosexual intercourse at least once a month in the next year.
• Is willing to enter data on a daily basis and perform pregnancy tests as requested by protocol.
• Is willing to complete a satisfaction survey at the end of her study participation.

You may not qualify if…

• Has EU-citizenship
• Has had a Depo-Provera injection in the last 10 months or has had less than three consecutive, spontaneous menstrual cycles since their last injection.
• Has had less than three consecutive, spontaneous menstrual cycles after removing a hormonal implant.
• Has had less than three consecutive, spontaneous menstrual cycles after the end of a pregnancy.
• Has had less than three consecutive, spontaneous menstrual cycles since she last breastfed.
• Has (or partner has) known fertility issues, such as infertility and sterilization, or have been advised by a healthcare professional that they may have difficulty conceiving for any reason.
• Has a medical condition possibly impacting fertility, i.e. endometriosis, a history of Pelvic Inflammatory Disease (PID), significant uterine fibroids or adenomyosis, or another diagnosed medical condition that they have been told affects fertility.
• Is regularly taking one of the following prescribed pharmaceutical medications known to be teratogenic (i.e., a medication that can cause birth defects):
• Isotretinoin (like Accutane, Absorica, Claravis, or Myorisan) for severe acne Valproic acid or divalproex sodium (like Depakote, Depakene, or Topamax) for seizures (epilepsy), migraines, or bipolar disorder Methotrexate (Trexall, Rheumatrex) or leflunomide (Arava) for autoimmune conditions ACE Inhibitors (like Lisinopril, Enalapril) or Angiotensin II Receptor Blockers (ARBs) (like Losartan, Valsartan) for high blood pressure or heart conditions Warfarin (Coumadin, Jantoven) for blood clot prevention

Where it is running

• Natural Cycles USA Corp — New York, New York, United States (enrolling)

Full record on ClinicalTrials.gov

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