News | Advances in Reproductive Immunology: How Does the Menstrual Cycle Affect Infection Defense and Pregnancy?
A study led by UW Medicine found that levels of key immune signaling molecules in the vagina fluctuate “clearly and consistently” across the menstrual cycle. Published in BMC Medicine, the findings may help researchers understand the immune system's role in reproduction and inform vaccine development and treatment of infectious diseases.
Rhythmic Immune Changes Across the Menstrual Cycle
The team conducted a meta-analysis of 32 studies and identified 53 different signaling molecules used for communication between immune cells. The vaginal immune system showed distinct changes at different stages of the menstrual cycle, potentially affecting women's health, fertility, and vaccine effectiveness.
“The body's cells communicate through cytokines, molecules that can signal immune cells with messages such as ‘there is an infection here’ or ‘everything is normal,’” explained lead author Sean Hughes, a research scientist in Obstetrics and Gynecology at the University of Washington School of Medicine.
Before ovulation, during the follicular phase, cytokines more frequently recruit macrophages to the vaginal area. This activity decreases after ovulation, during the luteal phase. Because implantation may occur during the luteal phase, this immune shift may reduce immune activity and support embryo implantation.
Key Findings for Vaccine Research and Reproductive Medicine
“We observed that many cytokine levels decreased during the luteal phase, consistent with previous findings that immune activity is reduced at this time. This change may facilitate implantation,” the authors wrote. “At the same time, antimicrobial factors such as beta-defensins increased during the luteal phase, potentially compensating for the lower immune activity.”
The finding expands understanding of the female immune system and suggests that researchers should consider menstrual-cycle stage when testing vaccines or other interventions.
“Scientists need to optimize study designs so all participants are tested at the same stage of the menstrual cycle, producing more accurate results,” said senior author Dr. Florian Hladik, research professor of Obstetrics and Gynecology at the University of Washington.
A Foundation for Future Research
Hughes said the study provides a strong reference describing how 53 cytokines change across the menstrual cycle. Researchers must now investigate why these changes occur and how they affect sexually transmitted infections and pregnancy.
“We now know the ‘what’ for 53 cytokines. The next step is understanding ‘why’ these changes occur and how they affect women's health,” Hughes said.
Overall, immune differences between the follicular and luteal phases may mean that vaccines or other medical interventions have different effects depending on cycle stage. The study therefore offers new directions for vaccine development and an important foundation for reproductive medicine and gynecologic care.
Story source:
Collected online
Published 2025-03-18
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News | Advances in Reproductive Immunology: How Does the Menstrual Cycle Affect Infection Defense and Pregnancy?
News | Advances in Reproductive Immunology: How Does the Menstrual Cycle Affect Infection Defense and Pregnancy?
A study led by UW Medicine found that levels of key immune signaling molecules in the vagina fluctuate “clearly and consistently” across the menstrual cycle. Published in BMC Medicine, the findings may help researchers understand the immune system's role in reproduction and inform vaccine development and treatment of infectious diseases.
Rhythmic Immune Changes Across the Menstrual Cycle
The team conducted a meta-analysis of 32 studies and identified 53 different signaling molecules used for communication between immune cells. The vaginal immune system showed distinct changes at different stages of the menstrual cycle, potentially affecting women's health, fertility, and vaccine effectiveness.
“The body's cells communicate through cytokines, molecules that can signal immune cells with messages such as ‘there is an infection here’ or ‘everything is normal,’” explained lead author Sean Hughes, a research scientist in Obstetrics and Gynecology at the University of Washington School of Medicine.
Before ovulation, during the follicular phase, cytokines more frequently recruit macrophages to the vaginal area. This activity decreases after ovulation, during the luteal phase. Because implantation may occur during the luteal phase, this immune shift may reduce immune activity and support embryo implantation.
Key Findings for Vaccine Research and Reproductive Medicine
“We observed that many cytokine levels decreased during the luteal phase, consistent with previous findings that immune activity is reduced at this time. This change may facilitate implantation,” the authors wrote. “At the same time, antimicrobial factors such as beta-defensins increased during the luteal phase, potentially compensating for the lower immune activity.”
The finding expands understanding of the female immune system and suggests that researchers should consider menstrual-cycle stage when testing vaccines or other interventions.
“Scientists need to optimize study designs so all participants are tested at the same stage of the menstrual cycle, producing more accurate results,” said senior author Dr. Florian Hladik, research professor of Obstetrics and Gynecology at the University of Washington.
A Foundation for Future Research
Hughes said the study provides a strong reference describing how 53 cytokines change across the menstrual cycle. Researchers must now investigate why these changes occur and how they affect sexually transmitted infections and pregnancy.
“We now know the ‘what’ for 53 cytokines. The next step is understanding ‘why’ these changes occur and how they affect women's health,” Hughes said.
Overall, immune differences between the follicular and luteal phases may mean that vaccines or other medical interventions have different effects depending on cycle stage. The study therefore offers new directions for vaccine development and an important foundation for reproductive medicine and gynecologic care.
Story source:
Collected online