"Menstrual Irregularities After Vaccination... Temporary Cycle Changes Possible, US Study Finds"

Vaccination. / Photo by Asia Economy

[Asia Economy Reporter Na Ye-eun] A study has found that COVID-19 vaccination can temporarily affect women's menstrual cycles. Women who received at least one dose of the vaccine experienced a delay of about one day in their menstrual cycle length compared to unvaccinated women.

On the 6th (local time), The New York Times (NYT) reported that a recent study published in an obstetrics and gynecology journal discovered changes in women's menstrual cycles after vaccination.

The study involved researchers from Oregon Health & Science University and Brown University's Warren Alpert Medical School, conducted in collaboration with 'Natural Cycles,' a fertility tracking app used by millions of women worldwide. The researchers examined records of about 4,000 U.S. women aged 18 to 45 who consented to provide information, including approximately 2,400 vaccinated and 1,550 unvaccinated participants.

The results showed that the menstrual cycle of vaccinated women was on average about one day longer, and this change was temporary. Additionally, women who received both vaccine doses within the same menstrual cycle experienced a delay of about two days. Since the second dose is administered three weeks after the first, and considering that the typical menstrual cycle is over 28 days, it is possible for women to receive two vaccine doses within one cycle.

Hugh Taylor, Chair of Obstetrics, Gynecology & Reproductive Sciences at Yale University, stated, "This is one of the first studies supporting women's reports of disrupted menstrual cycles after vaccination."

He added, "The changes observed in the study were not significant and appeared temporary. While one or two cycles deviating from the usual pattern may be inconvenient, medically it is unlikely to be harmful."

Reports of vaccine side effects related to menstruation submitted to health authorities worldwide have been more varied. Symptoms include irregular cycles, increased menstrual pain, and heavier bleeding. Some women even reported menstruating for the first time in years after menopause.

However, the NYT pointed out that "the study's participants were predominantly white Americans, making it difficult to generalize the findings." The study used data from Natural Cycles, whose users are mainly white, and the participants weighed less on average compared to typical American women.

This content was produced with the assistance of AI translation services.