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Individuals with COVID-19 may experience a slight increase in menstrual cycle length, comparable to the menstrual cycle increase seen among those who received a COVID-19 vaccine, according to a study funded by the National Institutes of Health. The study authors stressed that the increase was small and temporary.

Premenopausal females who were vaccinated for COVID-19 were no more likely to report irregular menstrual cycles, heavier bleeds or menstrual pain than a similar group of unvaccinated women, according to a study funded by the National Institutes of Health. However, consistent with several previous studies, participants reported a small increase in cycle length of roughly one day following injection.

Compared to unvaccinated women, women vaccinated for COVID-19 have a slightly higher risk of a heavier period after vaccination, suggests a study funded by the National Institutes of Health. However, flow returns to normal in the next menstrual period.

Read about NICHD’s research findings and activities from 2022.

A large international study has confirmed the findings of a previous U.S. study that linked COVID-19 vaccination with an average increase in menstrual cycle length of less than one day. The increase was not associated with any change in the number of days of menses (days of bleeding). Funded by the National Institutes of Health, the new study included data from nearly 20,000 people from Canada, the United Kingdom, the United States, Europe and other parts of the world who received any of nine different vaccines. For most study participants, the increase resolved in the cycle following vaccination.

Read about NICHD’s research findings and activities from 2021.

Women receiving one dose of a COVID-19 vaccine during a single menstrual cycle had an increase in cycle length of nearly one day, according to an NIH-funded study.

NICHD Director Dr. Diana W. Bianchi explains how menstruation provides insights into overall health status and encourages clinical researchers to routinely collect menstrual cycle data.

NIH has awarded one-year supplemental grants to five institutions to explore potential links between COVID-19 vaccination and menstrual changes.

Read about NICHD’s research findings and activities from 2020.

NICHD has supported gynecologic and reproductive health research for decades. Learn more about its leading role in menstruation research.

Women who breastfed their infants exclusively for 7 to 12 months may have a significantly lower risk of early menopause than their peers who breastfed their infants for less than a month, according to an analysis funded by the National Institutes of Health.

Carriers of the FMR1 premutation—a mutation in the gene associated with the developmental disorder Fragile X syndrome—may have a higher risk for several health conditions, according to an analysis funded by the National Institutes of Health.

In 2018, researchers funded by NICHD made significant progress in advancing the health and well-being of infants, children, teenagers, and adults across the United States and around the world.

Dr. Candace Tingen with NICHD’s Gynecological Health and Disease Branch speaks about the possibilities of tapping a woman’s menstrual cycle for signs of disease. Listen to our latest podcast.

The Gynecologic Health and Disease Branch recently published its scientific vision. The document summarizes its research themes, which provide direction for future research.

Insufficient sodium or manganese increases risk, NIH study suggests

Understanding endometriosis, causes and treatment, is part of NICHD’s mission. Learn more about signs and symptoms.