The effect of BNT162b2 SARS‐CoV‐2 mRNA vaccine on menstrual cycle symptoms in healthy women

Abstract

Objective To investigate the impact of the SARS‐CoV‐2 mRNA BNT162b2 vaccine on women’s menstural cycle. Methods In this questionnaire‐based cross‐sectional study, we assessed menstrual pattern and changes of women who completed the SARS‐CoV‐2 mRNA BNT162b2 vaccine three months before and after receiving the vaccine. Included were women aged 18‐50 without known gynecological comorbidities who regularly monitor their menstruation through electronic calendars. All participants competed a detailed questionnaire on their menstrual symptoms including information on any irregular bleeding. To minimize bias, each woman served as a self‐control before and after vaccination. Primary outcome was rate of irregular bleeding following vaccination and secondary outcome was presence of any menstrual change, including irregular bleeding, mood changes or dysmenorrhea following the vaccine. Results A total of 219 women met the inclusion critieria. Of them, 23.3% (n=51) experienced irregular bleeding following the vaccine. Almost 40% (n=83) of study participants reported any menstrual change following vaccination. Parity was positively asssociated with irregular bleeding with 50% (n=26) of those suffering from irregular bleeding being multiparous as compared to only 31.5% (n=53) of women with no irregular bleeding (nulliparous 46% vs 60%, multiparous 50% vs 31%, rest 4% vs 8%, p=0.049). The presence of medical comorbidities was also significantly higher among patients who experienced irregular bleeding (20.0% vs 6.0%, p=0.003). Conclusion Our study shows relatively high rates of irregular bleeding and menstrual changes after receiving the SARS‐CoV‐2 mRNA BNT162b2 vaccine. Further research is needed to confirm our findings and to better characterize the magnitude of change and any possible long term implications.

mRNA Vaccines against SARS-CoV-2: Advantages and Caveats

“…To date, although with less solid data, other consequences associated with the vaccines have been detected and reported. For example, alterations in the menstrual cycle such as abnormal bleeding and delayed menstruation following the second booster dose of the BNT162b2 vaccine [ 121 , 122 ]. Studies reporting the main adverse events are summarized in Table 2 .…”

Changes in Endometriosis-Associated Symptoms Following Immunization against SARS-CoV-2: A Cross-Sectional Study

“…Another study from Israel has reported the worsening of dysmenorrhea in the cohort with and without endometriosis, but the information about positive improvement are is [ 16 ]. Additionally, another study has reported new incidence or worsening of dysmenorrhea by more than 47% of participants during the COVID-19 pandemic [ 17 ]. In contrast, there are also studies reporting reduced occurrence or improvement in their symptoms following COVID-19 vaccination, similar to our results [ 11 , 18 ].…”

“…In contrast, there are also studies reporting reduced occurrence or improvement in their symptoms following COVID-19 vaccination, similar to our results [ 11 , 18 ]. However, the studies focusing on dysmenorrhea or back pain described above are very heterogenous regarding their methods; a few evaluated the intensity of the symptoms [ 16 , 17 ], others compared endometriosis patients vs. health controls [ 16 , 19 ], and only two of these studies followed the same approach that we used here and compared the occurrence of the symptoms before and after immunization [ 11 , 18 ]. The majority of our participants reported dysmenorrhea and back pain less frequently after immunization, but rarely, we also observed the reverse pattern, i.e., dysmenorrhea and back pain after but not prior to immunization, similar to our results regarding changes in menstrual bleeding reported elsewhere [ 5 ].…”

“…Comparable data regarding risk factors for emerging back pain after immunization against COVID-19 are rare. One study excluded patients with thyroid disease, others do not report on BMI or thyroid dysfunctions [ 16 , 17 , 18 , 19 ], and one study found no impact of BMI and thyroid disease on changes regarding dysmenorrhea and back pain following immunization against COVID-19 [ 11 ].…”

“…Taken together, the currently available published studies provide very heterogeneous results regarding changes in menstrual symptoms following immunization against COVID-19, partly due to different methodology and the use of surrogate parameters [ 17 , 19 , 23 , 24 , 25 ]. Several studies evaluated symptoms only in patients with endometriosis, but not in the general population [ 9 , 16 , 19 ].…”