The use of once daily basal body temperature (BBT) to identify the fertile window is wrought with user error and lack of precision. Alternatively, continuous, core body temperature allows one to identify patterns in temperature associated with circadian rhythm, including the transition of the follicular phase to luteal phase and its transient drop in temperature. This nadir occurs 1 to 2 days before the luteinizing hormone surge, providing a true predictor of a woman's fertile window. Prima-Temp has developed a self-inserted flexible vaginal ring that continuously monitors core body temperature, and passively communicates to a smartphone app.
This multi-site study compared ovulation predicted by this continuous core temperature sensor with: 1) daily oral BBT, 2) urine LH ovulation prediction kit, 3) serum progesterone levels, and 4) transvaginal ultrasound. 20 female subjects used the sensor for 3 menstrual cycles each. The study also identified user acceptance and ease of use of the vaginal ring.
Comparison between all methods was analyzed by the temporal relationship of a positive test given by each method from the true day of ovulation recorded by ultrasound. Statistics analyzed the ability of each method to identify ovulation via paired t test and multilevel model approach. The resulting novel sensor and algorithm correctly predicted ovulation.
This innovative sensor and its associated app will measure continuous core temperature and circadian rhythm providing a novel, safe, effortless and more accurate method of ovulation prediction.