COVID vaccine and the menstrual cycle — what did women report?

Aim of the study: The relationship between COVID-19 vaccines and menstrual disturbance is unclear, in part because researchers have measured different outcomes (e.g., delays vs. changes to cycle length) with various study designs. Menstrual disruption could be a decisive factor in people's willingness to accept the COVID-19 vaccine.

Results: Seventeen studies with >1·9 million participants were analyzed. We found a 19% greater risk of increase in menstrual cycle length as compared to unvaccinated people or pre-vaccination time-periods (summary relative risk (sRR): 1·19; 95% CI: 1·11-1·26; n = 23,718 participants). The increase in risk was the same for Pfizer-BioNTech (sRR: 1·15; 1·05-1·27; n = 16,595) and Moderna vaccines (sRR: 1·15; 1·05-1·25; n = 7,523), similar for AstraZeneca (sRR: 1·27; 1·02-1·59; n = 532), and higher for the Janssen (sRR: 1·69; 1·14-2·52; n = 751) vaccine. In the first cycle after vaccination, length increased by <half-day (summary mean difference (sMD): 0·34 days; 0·21-0·46 days; n = 30,320) after the first dose and by 0·62 days (sMD: 0·62: 0·41-0·82; n = 17,608) after the second dose. In the second cycle after vaccination, the risk was not elevated (sMD: -0·02; -0·16-0·12; n = 18,602).

Aim of the study: The objective of this systematic review is to give a comprehensive interpretation of menstrual cycle changes after the COVID-19 vaccination. Additionally, it is imperative to assess reports of menstrual changes following vaccination to dispel concerns that COVID-19 vaccines hinder the likelihood of pregnancy in the long run.

Results: Of these, 39 759 (52.05%) had some form of a menstrual problem after vaccination. Due to the lack of published research articles, preprints were also included in this review. Menorrhagia, metrorrhagia, and polymenorrhea were the most commonly observed problems and the overall study-level rate of menstrual abnormality ranged from 0.83% to 90.9%. Age, history of pregnancy, systemic side-effects of COVID-19, smoking, and second dose of COVID-19 vaccine were predictors of menstrual problems after vaccination.

Aim of the study: COVID - 19 vaccine can lead to various local and systemic side effects, including menstrual irregularities in women. There is no robust quantitative evidence of the association between the COVID - 19 vaccine and menstrual irregularities. A meta-analysis was performed to estimate the pooled prevalence of a range of menstrual disorders that may occur in women following COVID - 19 vaccination.

Results: Overall, the pooled prevalence of menorrhagia was 24.24 % (pooled prevalence 24.24 %; 95 % CI: 12.8-35.6 %). The pooled prevalence of polymenorrhea was 16.2 % (pooled prevalence: 16.2 %; 95 % CI: 10.7-21.6 %). The pooled prevalence of abnormal cycle length was relatively lower than that of the other disorders (pooled prevalence: 6.6 %; 95 % CI: 5.0-8.2 %). The pooled prevalence of oligomenorrhea was 22.7 % (95 % CI: 13.5-32.0 %). The findings indicate that menorrhagia, oligomenorrhea, and polymenorrhea were the most common menstrual irregularities after vaccination. The findings also suggest that a relatively high proportion of women suffer from menstrual irregularities. Further longitudinal studies are needed to confirm the causal relationship between COVID-19 vaccination and menstrual irregularities.

Aim of the study: We prospectively examined the association between COVID-19 vaccination and menstrual cycle characteristics in an internet-based prospective cohort study. We included a sample of 1,137 participants who enrolled in Pregnancy Study Online (PRESTO), a preconception cohort study of couples trying to conceive, during January 2021-August 2022.

Results: Participants had 1.1 day longer menstrual cycles after receiving the first dose of COVID-19 vaccine (95 % CI: 0.4, 1.9) and 1.3 day longer cycles after receiving the second dose (95 % CI: 0.2, 2.5). Associations were attenuated at the second cycle post-vaccination. We did not observe strong associations between COVID-19 vaccination and cycle regularity, bleed length, heaviness of bleed, or menstrual pain. In conclusion, COVID-19 vaccination was associated with a ∼1 day temporary increase in menstrual cycle length, but was not appreciably associated with other menstrual cycle characteristics.

Aim of the study: COVID-19 vaccination may be associated with change in menstrual cycle length following vaccination. We estimated covariate-adjusted differences in mean cycle length (MCL), measured in days, between pre-vaccination cycles, vaccination cycles, and post-vaccination cycles within vaccinated participants who met eligibility criteria in the Apple Women's Health Study, a longitudinal mobile-application-based cohort of people in the U.S.

Results: Cycles in which the single dose of J&J was administered were, on average, 1.26 days longer (95% CI: 0.45, 2.07) than pre-vaccination cycles. Post-vaccination cycles returned to average pre-vaccination length. Estimated follicular phase vaccination was associated with increased MCL in cycles in which participants received the first dose (0.97 days, 95% CI: 0.53, 1.42) or the second dose (1.43 days, 95% CI: 1.06, 1.80) of mRNA vaccines or the J&J dose (2.27 days, 95% CI: 1.04, 3.50), compared with pre-vaccination cycles. Menstrual cycle change following COVID-19 vaccination appears small and temporary and should not discourage individuals from becoming vaccinated.

Aim of the study: To assess whether coronavirus disease 2019 (COVID-19) vaccination is associated with changes in cycle or menses length in those receiving vaccination as compared with an unvaccinated cohort.

Results: We included 3,959 individuals (vaccinated 2,403; unvaccinated 1,556). Most of the vaccinated cohort received the Pfizer-BioNTech vaccine (55%) (Moderna 35%, Johnson & Johnson/Janssen 7%). Overall, COVID-19 vaccine was associated with a less than 1-day change in cycle length for both vaccine-dose cycles compared with prevaccine cycles (first dose 0.71 day-increase, 98.75% CI 0.47-0.94; second dose 0.91, 98.75% CI 0.63-1.19); unvaccinated individuals saw no significant change compared with three baseline cycles (cycle four 0.07, 98.75% CI -0.22 to 0.35; cycle five 0.12, 98.75% CI -0.15 to 0.39). In adjusted models, the difference in change in cycle length between the vaccinated and unvaccinated cohorts was less than 1 day for both doses (difference in change: first dose 0.64 days, 98.75% CI 0.27-1.01; second dose 0.79 days, 98.75% CI 0.40-1.18). Change in menses length was not associated with vaccination.

Aim of the study: Menstrual disorders were not reported as a possible secondary effect in any of the clinical trials for the SARS-CoV-2 vaccines. To describe the prevalence of perceived premenstrual and menstrual changes after COVID-19 vaccine administration.

Results: Of the women who participated in this study, 3136 reported no menstrual changes and 11,017 (78% of the study sample) reported experiencing menstrual cycle changes after vaccination. In summary, women who reported menstrual changes after vaccination were older (overall p < 0.001) and slightly more smokers (p = 0.05) than women who did not report any changes. The most prevalent changes in relation to premenstrual symptoms were increased fatigue (43%), abdominal bloating (37%), irritability (29%), sadness (28%), and headaches (28%). The most predominant menstrual changes were more menstrual bleeding (43%), more menstrual pain (41%), delayed menstruation (38%), fewer days of menstrual bleeding (34.5%), and shorter cycle length (32%). Women vaccinated against COVID-19 usually perceive mild menstrual and premenstrual changes. Future studies are warranted to clarify the physiological mechanisms behind these widely reported changes.

Aim of the study: To describe the characteristics of people who experience changes to their menstrual cycle after COVID-19 vaccination.

Aim of the study: To evaluate changes in the menstrual pattern of women of reproductive age infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or vaccinated against coronavirus disease 2019 (COVID-19).

Results: We received 1012 completed questionnaires and 735 (72.7%) were from women aged between 20 and 39 years, 745 (73.6%) were White and 491 (48.6%) lived with a partner. A total of 419 (41.6%) of the women reported SARS-CoV-2 infection; however, only two of them were hospitalized, and 995 (98.8%) of women had at least one dose of COVID-19 vaccine. About menstrual characteristics, 170 (41.3%) reported changes after having COVID-19 and 294 (29.9%) after COVID-19 vaccination, respectively. Few years of schooling, lower income, and non-white ethnicity were related to higher reports of menstrual changes after COVID-19. Menstrual changes after COVID-19 vaccination were associated with not using contraception. Higher body mass index was associated with irregularities in cyclicity and bleeding days, after COVID-19 and COVID-19 vaccination, respectively.

Aim of the study: Background: Some studies have suggested minor changes in the menstrual cycle after COVID-19 vaccination, but more detailed analyses of the menstrual cycle are needed to evaluate more specific changes in the menstrual cycle that are not affected by survey-based recall bias.

Results: Results: Of the 279 women who initiated the survey, 76 met the inclusion criteria and provided 588 cycles for analysis (227 pre-vaccine cycles, 145 vaccine cycles, 216 post-vaccine cycles). Although 22% of women subjectively identified changes in their menstrual cycle, there were no significant differences in menstrual cycle parameters (cycle length, length of menses, EOD, and luteal phase length) between the pre-vaccine, vaccine, and post-vaccine cycles. Conclusions: COVID-19 vaccines were not associated with significant changes in menstrual cycle parameters. Perceived changes by an individual woman must be compared with statistical changes to avoid confirmation bias.