COVID-19 vaccines may impact women's menstrual cycles: Study

A new study states that COVID-19 vaccines may affect a woman's menstrual cycle, according to a Saturday Forbes report.

Researchers at the Oregon Health & Science University in Portland, Oregon, carried out the study on a total of 3,959 U.S. women ages 18-45.

Some of the women were vaccinated and some of the women were not.

What are the details?

A recent study from medical journal Obstetrics & Gynecology states that the COVID-19 vaccine could possibly result in temporary changes to the onset of a woman's menstrual cycle.

For its results, the study's authors tracked the menstrual cycles of 3,959 participants over the course of six menstrual cycles. The women fell into two groups: vaccinated or unvaccinated.

The vaccinated group was made up of 2,403, women while the unvaccinated group was comprised of 1,556 women.

The study found that those who received their first dose of a COVID-19 vaccine waited 0.71 days longer on average for their next menstrual cycle when compared to their cycles before vaccination. The minimum increase, according to the report, was 0.63, days while the maximum delay was 1.19 days.

The study also noted that unvaccinated women with normal menstrual cycle histories experienced a 0.07-day increase in cycle length on average.

Researchers said that the delay of vaccinated women's menses appeared to be only temporary and noted that by two cycles later, the vaccinated group reverted to the length of their pre-vaccination cycles.

Alison Edelman, a professor of obstetrics and gynecology at Oregon Health & Science University, told the Wall Street Journal that the findings were "reassuring" because the change to a woman's menstrual cycle was only small and temporary.

“It’s reassuring that it’s small,” Edelman, who was also one of the researchers on the study, added. “It’s also validating to individuals who experienced [a delay in menses].”