The potential bidirectional relationship between long COVID and menstruation.

Area of Science:

• Reproductive Endocrinology
• Infectious Diseases
• Immunology

Background:

• Menstrual changes and cyclical symptom variation reported post-SARS-CoV-2 infection.
• Need to investigate links between COVID-19, long COVID, and menstrual health.

Purpose of the Study:

• Assess COVID-19's association with abnormal uterine bleeding (AUB).
• Determine if long COVID symptoms vary across the menstrual cycle.
• Explore potential underlying mechanisms.

Main Methods:

• UK population study comparing menstrual bleeding patterns in long COVID, acute COVID, and never-infected groups.
• Analysis of long COVID symptom severity across menstrual cycle phases in 54 women.
• Serum and endometrial tissue analysis for hormonal and inflammatory markers.

Main Results:

• Long COVID associated with increased menstrual volume, duration, and intermenstrual bleeding compared to uninfected individuals.
• Acute COVID recovery showed minimal menstrual disruption.
• Long COVID symptoms peaked during perimenstrual and proliferative phases.
• Elevated serum 5α-dihydrotestosterone and reduced endometrial androgen receptors in long COVID.
• Increased menstrual inflammation and immune cell aggregates in endometrium.

Conclusions:

• Long COVID is linked to AUB, but not impaired ovarian function.
• Peripheral and endometrial inflammation may drive AUB and long COVID symptom severity.
• Findings may inform new therapeutic strategies for women with long COVID.