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Flu Vaccines May Temporarily Alter Menstrual Cycles, Study Finds

4/29/2025

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Summary

Story summary

A groundbreaking study from Oregon Health & Science University reveals that seasonal flu vaccines may lead to slight, temporary extensions in menstrual cycle length, especially when given during the follicular phase. Encouragingly, no lasting effects on fertility were found, shedding light on vaccine-related menstrual health amid growing vaccine hesitancy.

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Story summary

A groundbreaking study from Oregon Health & Science University reveals that seasonal flu vaccines may lead to slight, temporary extensions in menstrual cycle length, especially when given during the follicular phase. Encouragingly, no lasting effects on fertility were found, shedding light on vaccine-related menstrual health amid growing vaccine hesitancy.