Measuring Core Body Temperature Using TempuRing

Inclusion Criteria: 1. Participant is willing and able to give informed consent for participation 2. Females aged 21 to 43 years 3. Have a body mass index (BMI) above 19 and below 29 4. Regular menstrual cycles, i.e. no greater than 7 days difference between the shortest and longest cycle in the last 6 months 5. Minimum menstrual cycle 24 days 6. Maximum menstrual cycle 35 days 7. Normal pap smear within the last year 8. Willing to use the fertility device for at least 3 cycles 9. Willing to fill in online questionnaires 10. Willing to attend clinic up to 6 times per cycle for transvaginal ultrasound and blood tests 11. Willing to perform LH urine tests at home twice a day from day 8 of cycle until it is positive 12. Willing to document the last day of the previous menses and first day of the following menses. 13. Willing to measure and record oral at the same time each morning. 14. Normal pelvic ultrasound and blood results obtained during screening tests Exclusion Criteria: 1. Any diagnosed systemic illnesses including thyroid disease, diabetes, yeast infection, Chlamydia, gonorrhea, trichomonas, bacterial vaginosis, inflammatory diseases, or are in an immuncompromised state 2. Polycystic ovary disease 3. Endometriosis or other chronic pelvic pain or pelvic pathology 4. Taking steroid medication, including oral contraceptives or anti inflammatory drugs 5. Pregnant