Flo Digital Contraceptive Study
ConditionContraception Use
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexFemale
Age18+
SponsorFlo Health Inc.
About this trial
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
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Adults with female reproductive organs aged ≥18 years
Reside in the United States of America
Have menstrual frequency (i.e., interval between first day of bleeding each cycle) between 16-90 days
Sexually active, having vaginal sex with male partner(s) without known fertility problems AND where neither partner has a known, or is at high risk of, sexually transmitted infections (STIs).
Disqualifiers
Oral contraceptive pills
Hormonal implants, injections, vaginal rings or transdermal patches
Intrauterine devices (copper and/or levonorgestrel)
Surgical sterilization (tubal ligation, salpingectomy, intrafallopian tube coils)
Trial design
Design model
Single group
Treatments tested in this trial
Flo Digital Contraceptive
DeviceThe 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.
Treatment groups
3,800 Participants
are divided into 1 treatment groupGroup A: Single Arm Device InterventionExperimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
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.Secondary outcomes
1
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.2
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.3
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.4
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.Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Flo Health Inc.
Lead sponsor
Lindus Health
Collaborator
Source ClinicalTrials.gov