ArticleNPJ digital medicine2022
Covid-19 vaccination and menstrual cycle length in the Apple Women's Health Study.
Article in NPJ digital medicine, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 42 papers, 4 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
42 citing papers in PubMed, 4 syntheses or guidelines pooled it, 60 citations in OpenAlex.
- Menstrual disturbance associated with COVID-19 vaccines: A comprehensive systematic review and meta-analysis.PloS one · 2025Pooled it
- Prevalence of menstrual alterations following COVID-19 vaccination: systematic review & meta-analysis.BMC women's health · 2024Pooled it
- Pooled it
- Menstrual disorders following COVID-19 vaccination: a review using a systematic search.Frontiers in drug safety and regulation · 2024Pooled it
- Inflammatory mechanisms of menstrual cycle changes following COVID-19 vaccination in adolescents.Vaccine · 2026Article
- Factors affecting menstrual cycle changes following COVID-19 vaccination in Korean women of reproductive age: an exploratory correlational study.Women's health nursing (Seoul, Korea) · 2025Article
- The menstrual cycle is a vital sign across the lifespan.The Lancet. Obstetrics, gynaecology, & women's health · 2025Article
- The potential bidirectional relationship between long COVID and menstruation.Nature communications · 2025Article
- Menstrual Disorders Following Covid 19 Vaccination in Women of Reproductive Age and Post-Menopause. A Systematic Review.Health science reports · 2025Review
- The Menstrual Cycle as a Vital Sign: a comprehensive review.F&S reviews · 2025Article
- Consensus recommendations for measuring the impact of contraception on the menstrual cycle in contraceptive clinical trials.Contraception · 2025Article
- Coronavirus disease vaccine linked menstrual changes: mobile application study.Obstetrics & gynecology science · 2025Article
- Impact of administration routes and dose frequency on the toxicology of SARS-CoV-2 mRNA vaccines in mice model.Archives of toxicology · 2025Article
- Bleeding Through a Pandemic: Women's Lived Experiences with Heavy Menstrual Bleeding During the COVID-19 Pandemic.International journal of women's health · 2025Article
- Brief report: Older adolescents and young adults may be at higher risk for changes to menstrual cycle length with COVID-19 vaccination.PloS one · 2025Article
- The Possible Mechanistic Basis of Individual Susceptibility to Spike Protein Injury.Advances in virology · 2025Review
- Association between the COVID-19 vaccination campaign and fertility trends: a population-level time series analysis for 22 countries.BMJ public health · 2025Article
- A Prospective Study of the Relationship of COVID-19 Vaccination to Menstrual Cycle Characteristics in Adolescent Girls.The Journal of adolescent health : official publication of the Society for Adolescent Medicine · 2024Article
- The association of COVID-19 vaccination and menstrual health: A period-tracking app-based cohort study.Vaccine: X · 2024Article
- Association between COVID-19 vaccination and menstruation: a state of the science review.BMJ sexual & reproductive health · 2024Review
Corrections and comments
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Authors and funding
14 authors at 3 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
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. with manually logged menstrual cycles. A total of 9652 participants (8486 vaccinated; 1166 unvaccinated) contributed 128,094 cycles (median = 10 cycles per participant; inter-quartile range: 4-22). Fifty-five percent of vaccinated participants received Pfizer-BioNTech's mRNA vaccine, 37% received Moderna's mRNA vaccine, and 8% received the Johnson & Johnson/Janssen (J&J) vaccine. COVID-19 vaccination was associated with a small increase in MCL for cycles in which participants received the first dose (0.50 days, 95% CI: 0.22, 0.78) and cycles in which participants received the second dose (0.39 days, 95% CI: 0.11, 0.67) of mRNA vaccines compared with pre-vaccination cycles. 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.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.