Heart Rate Variability During the Menstrual Cycle

This study is a prospective observational study of women's heart rate and heart rate variability throughout one complete menstrual cycle. A minimum of 10 volunteers aged 18 years of age or over will be recruited via a variety of methods according to the criteria detailed in section 9. They will be required to wear a chest heart rate monitor and wrist heart rate monitor for 1 hour each day, and throughout the night for one menstrual cycle. In addition, a daily early morning urine sample will be collected throughout the study.

Urine samples will be returned to SPD on a regular basis for measurement of urinary hormones related to pregnancy and fertility. Data collected via the monitors including heart rate and heart rate variability will be downloaded for comparison.

Primary outcomes

• Heart rate [1 month]: Heart rate at time points throughout the menstrual cycle
• Heart Rate [1 month]: Heart rate variability at time points throughout the menstrual cycle
• Day of Ovulation [1 month]: Day of ovulation determined by urinary LH surge +1 day
• Fertile Window [1 month]: Fertile window onset determined by E3G surge
• Fertile window [1 month]: Fertile window closure determined by P3G rise

Secondary outcomes

• Comparisons between wrist and chest band monitors [1 month]: Agreement between wrist band and chest band heart rate data

Sex: Female, ages: 18 Years to any

Inclusion Criteria:

* Aged 18 years of age and over
* Regular menstrual cycles (23-35 days in length)-

Exclusion Criteria:

* Taking any hormonal medications
* Taking any medications that may affect heart rate
* Known heart condition or use of a pacemaker
* Skin condition where there is sensitivity to wearing a skin monitor
* Currently suffering with anxiety or panic attacks
* Pregnant or breastfeeding
* Undertaking any frequent travel or long-haul flights during the course of the study
* Does not have access to an Apple iPhone or iPad with Bluetooth 4.0 (or later) and iOS 10.0 (or later)

• Sarah Johnson, Study director, SPD Development Company