In this study, women will be required to wear a heart rate monitor continuously and collect daily early morning urine samples for the duration of one complete menstrual cycle. This will enable comparisons between data collected from the heart rate monitor and hormone analysis in urine samples to be made.

This pilot 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 heart rate monitor continuously and collect daily early morning urine samples throughout one menstrual cycle.

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 monitor including heart rate and heart rate variability will be downloaded for comparison.

Inclusion Criteria:

• Age 18 years and over
• Regular menstrual cycles

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

Healthy volunteers