An interventional study of Flo Digital Contraceptive in Contraception Use, sponsored by Flo Health Inc.. Recruiting at 1 site in United States. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-05.
Sponsored by Flo Health Inc. · Not applicable, Interventional, and Treatment
The goal of this clinical trial is to learn if the Flo Digital Contraceptive (FDC) app can effectively prevent unintended pregnancy in women aged 18 years and older residing in the United States. The main questions it aims to answer are:
What is the rate of unintended pregnancy in women aged 18-35 years using FDC as their sole method of contraception under typical-use conditions, measured using the Pearl Index? What is the cumulative probability of unintended pregnancy over 13 menstrual cycles for all participants, including those with regular and irregular cycles?
Participants will:
Use the Flo Digital Contraceptive app in 'prevent pregnancy' mode as their primary method of contraception for up to 13 menstrual cycles or 18 months, whichever comes first Wear an Apple Watch (Series 8 or later, or Ultra) while sleeping to collect nightly wrist temperature data, which the app uses to detect ovulation Log menstrual cycles, sexual activity, and any use of emergency contraception directly in the Flo app Complete monthly electronic surveys (ePROs) administered by the study team covering pregnancy status, adherence, safety, and experience Complete a baseline demographic survey at enrollment and an exit survey at the end of participation
Study Overview The FOCUS trial (Flo Contraceptive US Study) is a prospective, single-arm, non-randomized, decentralized clinical study evaluating the contraceptive safety and effectiveness of the Flo Digital Contraceptive (FDC) - a fertility awareness-based Software as a Medical Device (SaMD) - in preventing unintended pregnancy. The study is sponsored by Flo Health Inc. and conducted by Lindus Health Ltd. as the Contract Research Organization (CRO), with participant recruitment across the United States.
The FDC is a proprietary machine-learning algorithm integrated within the Flo Period \& Cycles Tracker app (iOS). It uses menstrual cycle history and physiological indicators of ovulation - primarily overnight wrist-skin temperature measured via Apple Watch (Series 8 or later, or Ultra), with optional urinary luteinizing hormone (LH) tests - to dynamically classify each day of the user's cycle as either 'Not fertile' (unprotected intercourse permitted) or 'Use protection' (abstinence or barrier contraception required).
The FDC operates as an API-based SaMD integrated within the Flo app as the target user interface. The algorithm predicts daily fertility based on user-provided inputs, with predictions dynamically updated as new data is received. Wrist-skin temperature is continuously monitored throughout sleep, which accommodates variable sleep schedules and is a reliable method for detecting biphasic temperature patterns associated with ovulation. For participants with irregular cycles, the FDC algorithm adaptively expands the 'Use protection' window in proportion to detected cycle length variability. Following enrollment confirmation and FDC device activation, participants log menstrual period dates, sexual activity (including whether barrier methods were used), and any use of emergency contraception in the Flo app. Participants are followed for up to 13 menstrual cycles or 18 months from device activation, whichever occurs first.
Study Objectives The primary objective is to evaluate the typical-use contraceptive effectiveness of FDC in preventing unintended pregnancy among women aged 18-35 years with regular menstrual cycles (21-35 days), using the Pearl Index assessed against a pre-specified clinically acceptable upper limit of 10 pregnancies per 100 woman-years. A supporting secondary analysis uses Kaplan-Meier life-table methodology to estimate cumulative pregnancy probability over 13 cycles for all participants, assessed against a pre-specified cumulative threshold of less than 10%. Participants will be censored from the life-table analysis for voluntary withdrawal, loss to follow-up, study completion, or ineligibility.
Secondary objectives will evaluate perfect-use effectiveness of FDC in the highest-risk population (aged 18-35 years), and typical-use and perfect-use effectiveness of FDC in the full intended-use population (aged 18 years and older), using the same statistical approaches.
Exploratory objectives will evaluate typical-use effectiveness across pre-specified subgroups: cycle regularity (regular vs. irregular), Flo user status at enrollment (existing vs. new), and recency of hormonal contraceptive discontinuation (within vs. beyond 3 months prior to enrollment).
Sample size Target enrollment is 3,800 participants, determined by the more conservative of two sample size calculations. The Pearl Index analysis requires approximately 900 participants (568 woman-years of exposure), while the Kaplan-Meier analysis requires 3,800 participants to achieve 80% power. A per-cycle dropout rate of 8% is assumed, corresponding to approximately 66% cumulative attrition by cycle 13.
Safety Monitoring Given that FDC is a SaMD with no direct physiological interaction, the primary safety concern in this study is unintended pregnancy. This risk is monitored continuously through multiple safeguards including monthly pregnancy surveillance via ePRO and Flo app logging, participant-initiated reporting, and regular independent review by a Data Safety and Monitoring Board (DSMB).
Regulatory and Ethical Oversight FOCUS is classified as a significant risk device study under 21 CFR Part 812. Enrollment will not commence until Institutional Review Board (IRB) approval has been obtained and FDA has granted IDE authorization. Informed consent is obtained electronically via Florence Healthcare in a fully asynchronous, documented process compliant with 21 CFR Part 11. Results will be publicly disclosed regardless of outcome in accordance with regulatory requirements and Good Publication Practice guidelines.
This is the only study on the registry with Flo Health Inc. as lead sponsor.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Users exposed to the Flo Digital Contraceptive
Device: Flo Digital Contraceptive
The Flo Digital Contraceptive (FDC) is a fertility awareness-based Software as a Medical Device (SaMD) integrated within the Flo Period \& Cycles Tracker app (iOS) in 'prevent pregnancy' mode. The FDC uses a proprietary machine-learning algorithm to classify each day of the user's menstrual cycle as either 'Not fertile' (unprotected intercourse permitted) or 'Use protection' (abstinence or barrier contraception required). Classifications are generated dynamically using menstrual cycle history and overnight wrist-skin temperature measured via Apple Watch (Series 8 or later, or Ultra), synchronized daily through Apple Health, with optional urinary LH test results as a supplementary input. Participants use FDC as their sole method of contraception for up to 13 menstrual cycles or 18 months from device activation, whichever occurs first.
Also known as: FDC
Typical-Use Pearl Index in Women Aged 18-35 Years with Regular Menstrual Cycles
The Pearl Index (PI) is calculated as the number of unintended pregnancies per 100 woman-years of FDC exposure, assessed under typical-use conditions in women aged 18-35 years with regular menstrual cycles (21-35 days). An unintended pregnancy is defined as a documented positive pregnancy test occurring during active FDC use. Exposure time is calculated from the date of first FDC use (device activation) until confirmed pregnancy, intentional discontinuation, loss to follow-up, completion of 13 cycles, or study end, whichever occurs first. The PI is calculated with 95% exact Poisson confidence intervals. Effectiveness is concluded if the upper bound of the two-sided 95% CI is below the pre-specified clinically acceptable threshold of 10 pregnancies per 100 woman-years.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Typical-Use Cumulative Pregnancy Probability Over 13 Cycles in Women Aged 18-35 Years (All Cycles)
Kaplan-Meier life-table analysis estimating the cumulative probability of unintended pregnancy over 13 menstrual cycles under typical-use conditions in women aged 18-35 years, including participants with both regular and irregular cycles. Each menstrual cycle is treated as a discrete time interval. Participants are censored at voluntary withdrawal, loss to follow-up, ineligibility, or study end. Cumulative pregnancy probability at 13 cycles is presented with 95% confidence intervals calculated using Greenwood's variance estimator. Effectiveness is concluded if the upper bound of the two-sided 95% CI for cumulative pregnancy probability at 13 cycles is below 10%.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Perfect-Use Pearl Index in Women Aged 18-35 Years with Regular Menstrual Cycles
The Pearl Index calculated under perfect-use conditions in women aged 18-35 years with regular menstrual cycles (21-35 days). Perfect-use cycles are those in which app logs confirm consistent adherence to FDC guidance: unprotected intercourse occurred only on days classified as 'Not fertile', and intercourse on 'Use protection' days was protected by a barrier method. Participants are censored at the first imperfect-use cycle, confirmed pregnancy, or end of observation. The PI is calculated with 95% exact Poisson confidence intervals against the pre-specified clinically acceptable threshold of 10 pregnancies per 100 woman-years.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Perfect-Use Cumulative Pregnancy Probability Over 13 Cycles in Women Aged 18-35 Years (All Cycles)
Kaplan-Meier life-table analysis estimating the cumulative probability of unintended pregnancy over 13 menstrual cycles under perfect-use conditions in women aged 18-35 years, including participants with both regular and irregular cycles. Perfect-use cycles are those in which app logs confirm consistent adherence to FDC guidance throughout. Participants are censored at the first imperfect-use cycle, confirmed pregnancy, loss to follow-up, or study end. Cumulative pregnancy probability at 13 cycles is presented with 95% confidence intervals calculated using Greenwood's variance estimator.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Typical-Use Pearl Index in the Full Intended-Use Population (Aged 18+) with Regular Menstrual Cycles
The Pearl Index calculated under typical-use conditions in all enrolled participants aged 18 years and older with regular menstrual cycles (21-35 days), representing the full intended-use population of FDC as an over-the-counter contraceptive device. Unintended pregnancy is defined as a documented positive pregnancy test occurring during active FDC use. Exposure time is calculated from device activation until confirmed pregnancy, intentional discontinuation, loss to follow-up, completion of 13 cycles, or study end. The PI is calculated with 95% exact Poisson confidence intervals against the pre-specified clinically acceptable threshold of 10 pregnancies per 100 woman-years.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Typical-Use Cumulative Pregnancy Probability Over 13 Cycles in the Full Intended-Use Population (Aged 18+, All Cycles)
Kaplan-Meier life-table analysis estimating the cumulative probability of unintended pregnancy over 13 menstrual cycles under typical-use conditions in all enrolled participants aged 18 years and older, including those with both regular and irregular cycles. Each menstrual cycle is treated as a discrete time interval. Participants are censored at voluntary withdrawal, loss to follow-up, ineligibility, or study end. Cumulative pregnancy probability at 13 cycles is presented with 95% confidence intervals calculated using Greenwood's variance estimator, assessed against a pre-specified clinically acceptable upper limit of 10%.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Perfect-Use Pearl Index in the Full Intended-Use Population (Aged 18+) with Regular Menstrual Cycles
The Pearl Index calculated under perfect-use conditions in all enrolled participants aged 18 years and older with regular menstrual cycles (21-35 days). Perfect-use cycles are those in which app logs confirm consistent adherence to FDC guidance throughout: unprotected intercourse occurred only on 'Not fertile' days, and intercourse on 'Use protection' days was protected by a barrier method. Participants are censored at the first imperfect-use cycle, confirmed pregnancy, or end of observation. The PI is calculated with 95% exact Poisson confidence intervals against the pre-specified clinically acceptable threshold of 10 pregnancies per 100 woman-years.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Perfect-Use Cumulative Pregnancy Probability Over 13 Cycles in the Full Intended-Use Population (Aged 18+, All Cycles)
Kaplan-Meier life-table analysis estimating the cumulative probability of unintended pregnancy over 13 menstrual cycles under perfect-use conditions in all enrolled participants aged 18 years and older, including those with both regular and irregular cycles. Perfect-use cycles are those in which app logs confirm consistent adherence to FDC guidance throughout. Participants are censored at the first imperfect-use cycle, confirmed pregnancy, loss to follow-up, or study end. Cumulative pregnancy probability at 13 cycles is presented with 95% confidence intervals calculated using Greenwood's variance estimator, assessed against a pre-specified clinically acceptable upper limit of 10%.
Time frame: Up to 13 menstrual cycles or 18 months from FDC activation, whichever occurs first.
Plan to share: No
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