OBJECTIVE:

Identify whether vaccination against COVID-19 is associated with changes in menstrual pattern.

MATERIALS AND METHODS:

An anonymous observational, cross-sectional to be held from October 4 to 29, 2021 was conducted in a group of women who completed a questionnaire designed to inquire about changes in the menstrual cycle following vaccination. The survey was administered over a four-week period. SPSS software was used for statistical analysis. Changes before and after the application of the first and second doses of COVID-19 vaccine were evaluated with a paired samples t-test and 2.

RESULTS:

4501 patients were collected of whom 1815 were excluded because they did not meet the inclusion criteria; in the end 2686 remained for analysis. Of these, 37.9% (n = 1018) had changes in the menstrual cycle following COVID-19 vaccination; in 61.8% (n = 630) it was in the amount of bleeding. Of the women who reported menstrual cycle changes, 64.34% (n = 655) were after application of messenger RNA vaccines (35.06%; p = 0.19, 95%CI: -0.35-0.19). In relation to the number of doses applied 72.10% (n = 734) reported modifications in the menstrual cycle after l second vaccine (p = 0.01, CI95%: 0.58-0.98).

CONCLUSIONS:

Vaccination against COVID-19 is associated with small changes in the menstrual cycle, without statistical significance. Women receiving two doses of vaccine had changes in the amount of bleeding.