COVID 19 vaccine increases menstrual cycle length, study finds

COVID 19 vaccine increases menstrual cycle length, study finds

Washington US January 15 ANI Women receiving one dose of a COVID 19 vaccine during a single menstrual cycle had an increase in cycle length of nearly one day, compared to unvaccinated women, a recent study found.

The increase in cycle length a longer time between bleeding was not associated with a change in the number of days of menses days of bleeding. The study was published in the Obstetrics Gynecology Journal''.

The authors, led by Alison Edelman, M.D. H., of Oregon Health Science University, Portland, noted that menstrual cycles can vary a small amount from month to month, and the increase they saw was well within the range of normal variability.

They added that additional research is needed to determine how COVID-19 vaccination could potentially affect other menstrual characteristics, such as associated symptoms pain, mood changes, etc. It is reassuring that the study found only a small, temporary menstrual change in women, said Diana W. Bianchi, M.D., and other characteristics of bleeding including heaviness of flow. She said that the results provide women with the opportunity to plan accordingly, for the first time, as the director of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development NICHD.

Dr Bianchi said little research has been done before on how vaccines for COVID 19 or vaccines for other diseases could potentially affect the menstrual cycle.

The study authors looked at data from a fertility tracking app, Natural Cycles. Users can consent to the use of their own data on their menstrual cycles and their own data for research. For vaccinated individuals, the data was from three consecutive cycles before vaccination and from three more consecutive cycles, including the cycle or cycles in which the vaccine took place.

Data was collected for six consecutive cycles for unvaccinated individuals. Of the 3,959 people in the study, 2,403 were vaccine-vaccinated and 1,556 were unvaccinated.

The Pfizer and Moderna vaccines were given to most of the people who were vaccinated. On average, the first vaccine dose was associated with a 71 day cycle increase in cycle length and the second dose with a 91 day increase.

The increase in the vaccination cycle was less than one day for users who had been vaccinated over two cycles. There were no changes in the number of menstrual bleeding days for the vaccinated individuals. The researchers found no significant change in cycle length for the unvaccinated app users.

A subgroup of app users who received two vaccine doses in the same menstrual cycle 358 users had a larger average increase in cycle length of two days. The change appeared to decrease in subsequent cycles, indicating that the menstrual changes are likely to be temporary.