This study aims to find out whether menstrual blood can provide similar useful biological information to a standard blood sample taken from a vein in the arm as well as uterine biopsies and vaginal swabs.

Menstrual and reproductive health have historically been under-represented in research, and menstrual blood remains an under-studied biological sample despite its potential value for understanding women's health.

Women aged 18 years and over who are currently menstruating may be invited to take part. Participants will attend a study visit during their menstrual period, where they will provide a menstrual blood sample collected using a menstrual cup and a small blood sample from a vein in the arm.The samples will be sent to a research laboratory and analysed to compare the biological information they contain.

Some samples may also be processed to extract DNA and isolate cells for research purposes.

The study is low risk and is not expected to provide a direct medical benefit to participants. However, it may help improve understanding of whether menstrual blood could be used more widely in future women's health and fertility research. Participants will not receive individual results, as the tests are for research purposes only and are not designed to provide clinical information about their health.

The main aim of this study is to find out whether menstrual blood collected using a menstrual cup can provide similar useful biological information to a standard blood sample taken from a vein in the arm as well as self-administered vaginal swabs and uterine biopsies.The secondary aims of the study are to assess how practical and acceptable it is to collect menstrual blood in a clinic setting, whether these samples can be processed reliably in the laboratory, and whether menstrual blood contains similar useful biological information to a standard blood sample.Menstrual blood is an under-studied biological sample that may contain useful information about reproductive health and general biological processes. At present, standard blood samples are commonly used in research, additionally vaginal swabs and uterine biopsies are invasive techniques but menstrual blood may provide similar or additional information in a less invasive and more relevant way for some aspects of women's health.

There is currently limited evidence on whether menstrual blood can be collected, processed and analysed reliably for this purpose. This study is therefore needed to assess whether menstrual blood could be used alongside or in some cases instead of standard blood sampling in future women's health research.This is a multi-centre observational research study involving women aged 18 years and over who are currently menstruating. Participants will be recruited through participating fertility clinics.

Potential participants will be provided with a Participant Information Sheet and given time to consider participation.

Those who agree to take part will provide written informed consent before any study procedures are carried out.

Participants will attend a study visit during menstruation. At this visit, a trained member of staff will collect a small blood sample from a vein in the arm, this is part of a standard routine care blood draw. Participants will also provide a menstrual blood sample collected using a menstrual cup and a self administered vaginal swab All samples will be labelled with a unique study code and transferred to the research laboratory for processing and analysis. The study will compare information obtained from menstrual blood and standard blood samples to assess whether menstrual blood can be used as a useful biological sample for research. Some samples may be analysed immediately, while others may be stored temporarily as part of this ethically approved study. Samples will also undergo DNA extraction and cell isolation for research purposes.

There are no follow-up visits planned as part of this study, and participants will not receive individual test results.

Participation ends once the study samples have been collected. However some follow up appointments may be required for example if insufficient sample is obtained first time.

Inclusion Criteria:Are female and aged 18 years or over Experienced menarche but not menopause Are willing and able to provide a menstrual blood sample collected using a menstrual cup Are willing to provide a self-administered vaginal swab Are willing and able to undergo collection of a peripheral venous blood sample Are able to understand the study procedures and requirements Are able and willing to provide written informed consent Are willing for their samples and associated study data to be used for the research purposes described in the study documentation Participants may be recruited from participating fertility clinics.

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Exclusion Criteria:

• Are male or 17 years or younger Not experienced menarche or experienced menopause Currently pregnant Have an active vaginal, pelvic or systemic infection that may affect safe participation or sample integrity

Have a known allergy, sensitivity or intolerance to the menstrual cup material Have any medical, anatomical or physical condition that would make use of a menstrual cup unsafe or impractical Have any condition which, in the opinion of the investigator or delegated clinician, would make participation unsafe, inappropriate or unsuitable Are unable or unwilling to provide written informed consent

Women who have been through menarche and are considering fertility treatment, and menstruate without debilitating gynecological conditions