Effect of COVID-19 vaccination on the timing and flow of menstrual periods in two cohorts
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Abstract
COVID-19 vaccination protects against the potentially serious consequences of SARS-CoV-2 infection, but some people have been hesitant to receive the vaccine because of reports that it could affect menstrual bleeding. To determine whether this occurs we prospectively recruited a cohort of 79 individuals, each of whom recorded details of at least three consecutive menstrual cycles, during which time they each received at least one dose of COVID-19 vaccine. In spontaneously cycling participants, COVID-19 vaccination was associated with a delay to the next period, but this change reversed in subsequent unvaccinated cycles. No delay was detected in those taking hormonal contraception. To explore hypotheses about the mechanism by which these menstrual changes occur, we retrospectively recruited a larger cohort, of 1,273 people who had kept a record of their menstrual cycle and vaccination dates. In this cohort, we found a trend toward use of combined hormonal contraception being protective against reporting a delayed period, suggesting that menstrual changes following vaccination may be mediated by perturbations to ovarian hormones. However, we were unable to detect a clear association between the timing of vaccination within the menstrual cycle and reports of menstrual changes. Our findings suggest that COVID-19 vaccination can lengthen the menstrual cycle and that this effect may be mediated by ovarian hormones. Importantly, we find that the menstrual cycle returns to its pre-vaccination length in unvaccinated cycles.
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SciScore for 10.1101/2022.03.30.22273165: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization Where significant changes were found, sensitivity analyses were carried out by assuming that every participant who had not returned their journal had experienced scores for every cycle with the same distribution as the pre-vaccine cycle scores recorded by those who did return their journals: the distribution was produced by randomly selecting a score from the pre-vaccine cycle data distribution for each missing value. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Analysis was carried out and graphs generated using Graphpad Prism 9.0.0. Graphpad Prismsuggested: …SciScore for 10.1101/2022.03.30.22273165: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization Where significant changes were found, sensitivity analyses were carried out by assuming that every participant who had not returned their journal had experienced scores for every cycle with the same distribution as the pre-vaccine cycle scores recorded by those who did return their journals: the distribution was produced by randomly selecting a score from the pre-vaccine cycle data distribution for each missing value. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Analysis was carried out and graphs generated using Graphpad Prism 9.0.0. Graphpad Prismsuggested: (GraphPad Prism, RRID:SCR_002798)Results from OddPub: Thank you for sharing your data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:However, there are also a number of important weaknesses. Because the cohort is small, we may not have been able to detect real effects of vaccination on menstrual flow, or real relationships between menstrual and non-menstrual side effects. Some bias is also likely to have been introduced because it is unlikely that the participants who did not return their sheets did so at random, although we did attempt to account for this with a sensitivity analysis. Some bias is also likely to be introduced because “expected date of period” and “menstrual flow” are at least partially subjective, so there is the potential for participant’s expectations of how vaccination will impact their periods to impact their reports. In conclusion, in this small, prospectively-recruited cohort, we found that both the first and second doses of the COVID-19 vaccine were associated with a small delay to the subsequent period. This delay was not reported in interdose and post-vaccination cycles, suggesting that any changes are temporary. We were unable to detect changes to menstrual flow. These findings are reassuring, but work in larger prospectively-recruited cohorts is needed to more accurately determine how vaccination affects menstrual parameters.
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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