The study will recruit participants from two long-running birth cohort studies: Children of the 90s in south-west England and Born in Bradford in West Yorkshire.

Thousands of volunteers will use a specialist app and detailed questionnaires to record symptoms, sleep, mood, energy levels and overall wellbeing.

Participants will also provide menstrual fluid samples over three menstrual cycles using specially designed period pads.

By linking those samples with long-term health information and genetic data already held by the cohort studies, researchers hope to uncover biological signals associated with heavy menstrual bleeding.

They believe the findings could lead to earlier diagnosis, more personalised treatment plans and new methods of identifying health risks linked to heavy periods, including iron deficiency.

The project is being led by Sharp, an epidemiologist at the University of Exeter who specialises in women’s health research.

She said: “HMB is excessive menstrual blood loss that interferes with your physical, social, emotional and/or quality of life.

“It can occur with or without underlying pathology such as fibroids, hormonal issues.

“Common symptoms can often include: bleeding lasting longer than seven days, needing to change protection every one to two hours, passing large clots, signs of iron deficiency anaemia (e.g. fatigue, dizziness).”

The study is part of a wider international programme known as The Missed Vital Sign,, external led by Wellcome Leap, which aims to dramatically reduce the time women wait for effective treatment for heavy menstrual bleeding.

Professor Sharp said CycleTrack would be the largest bank of dried menstrual fluid samples in the world.

She added: “We’ll be able to understand what causes different conditions, like endometriosis, fibroids, the impact of those conditions on other areas of life, and then hopefully new ways to predict, prevent, and treat those symptoms as well.”