First author (reference) | Publication year | Study design | Location | Sample size | Age of participants | Study period | Vaccine types | Outcome(s) | Control variables | Main results | Overall risk of bias rating |
Alvergne19 | 2022 | Two cohorts: retrospective+prospective | UK | Prospective: 79 Retrospective: 1273 | ≥18 years | Retrospective: 7/2021–10/2021 Prospective: not provided | Pfizer, Moderna, AstraZeneca, Janssen | Timing and flow of menses | None |
| High |
Bouchard58 | 2022 | Prospective cohort | North America | 76 | 18–42 years | Not provided | Pfizer or Moderna mRNA vaccines | Prospectively collected daily diary data on: cycle length, days of flow, volume, luteal phase length, signs of ovulation. Secondary outcomes: perceived menstrual changes attributed to vaccination | None (time-invariant variables controlled as part of pre–post design) | 75 women provided 588 cycles for analysis (227 pre-vaccine cycles, 145 vaccine cycles, 216 post-vaccine cycles). 22% perceived changes in their menstrual cycle post-vaccination but there were no significant differences in menstrual cycle length or days of flow comparing pre-vaccine, vaccine and post-vaccine cycles | Moderate |
Chiang20 | 2023 | Prospective cohort study | Taiwan | 20 | ≥20 years | Not provided | Moderna, Pfizer, AstraZeneca | Cycle length, bleed length | None (pre–post design) | Bleed length: 6.08 (pre) vs 6.45 (first dose) vs 6.00 days (second dose). Cycle length: 29.42 (pre) vs 30.84 (first dose) vs 30.30 days (second dose) | High |
Duijster59 | 2023 | Prospective cohort event monitoring study+spontaneous reports | The Netherlands | 13 567 | 16–55 years | 1/2/2021–29/3/2022 | AstraZeneca, Janssen, Moderna or Pfizer vaccine | Amenorrhoea/oligomenorrhoea, dysmenorrhoea, heavy menstrual bleeding, intermenstrual bleeding, irregular bleeding, reduced blood loss, and withdrawal blood loss abnormal | Age | Increased odds of any menstrual abnormality for Janssen (OR 1.83; 95% CI 1.33 to 2.49), Moderna (OR 2.44; 95% CI 1.86 to 3.20) and Pfizer (OR 3.04; 95% CI 2.36 to 3.93) vs AstraZeneca. Most menstrual abnormalities (63.8%, n=352) occurred after second dose of vaccination vs first dose (36.2%). Overall, median time to resolution of abnormalities was 7 days (IQR 4–14 days) | Moderate |
Edelman15 | 2022 | Prospective cohort study | Global | 19 622 | 18–45 years | 10/2020–11/2021 | Pfizer, Moderna, AstraZeneca, Janssen | Cycle length, menses length | Age, BMI, education, parity, relationship status, global region | Adjusted difference (β) in change in cycle length between vaccinated and unvaccinated: first dose: 0.71 (95% CI 0.47 to 0.96); second dose: 0.56 (95% CI 0.28 to 0.84). After second dose: −0.11 (95% CI −0.33 to 0.10). Adjusted difference in change in menses length for vaccinated vs unvaccinated:first dose: 0.07 (95% CI 0.00 to 0.13); second dose: 0.13 (95% CI 0.06 to 0.20) | Low |
Edelman14 | 2022 | Prospective cohort study | US | 3959 | 18–45 years | 10/2020-9/2021 | Pfizer, Moderna, Janssen | Cycle length, menses length | Age, race/ ethnicity, BMI, parity, relationship status, education | Cycle length: first dose: β=0.64 (0.27 to 1.01); second dose: β=0.79 (0.40 to 1.18); Days of flow: first dose: β=0.08 (–0.04 to 0.19); second dose: β=0.08 (–0.04 to 0.20) | Low |
Gibson16 | 2022 | Prospective cohort study | US | 9652 | ≥18 years | 11/2019–1/2022 | Moderna, Pfizer, Janssen | Cycle length | Age, BMI, seasonality | All vaccinations: first dose of mRNA vaccine (0.50 days, 95% CI 0.22 to 0.78); second dose of mRNA vaccine (0.39 days, 95% CI 0.11 to 0.67); Janssen vaccine: 1.26 days longer (95% CI 0.45 to 2.07) than pre-vaccination cycles. Follicular phase vaccination: first dose of mRNA vaccine (0.97 days, 95% CI 0.53 to 1.42); second dose of mRNA vaccine (1.43 days, 95% CI 1.06 to 1.80); Janssen dose (2.27 days, 95% CI 1.04 to 3.50) | Low |
Mohr-Sasson17 | 2023 | Prospective cohort | Israel | 35 | 12–16 years | 6/2021–7/2021 | Pfizer | Change in: cycle regularity, cycle length, cycle intensity, AMH during 3-month period | Age, BMI, side effects | 31.8% of regularly menstruating girls had irregular periods after vaccination; 50% of pre-menarcheal girls reported menarche on 3- month follow-up; AMH levels not appreciably different pre- and post-vaccination | High |
Rogers23 | 2022 | Prospective cohort | UK | 11 475 | 18–59 years | 2/2021–10/2021 | AstraZeneca, Pfizer, SpikeVax | Cycle changes | None | Reported HR for first dose of AstraZeneca (reference) with second dose of AstraZeneca, first dose of Pfizer, and second dose of Pfizer. All null | Moderate |
Wang21 | 2022 | Prospective cohort study | US and Canada | 3858 | 21–56 years (all premenopausal) | 4/2020–11/2021 | mRNA and adenovirus-vector | Cycle length | Sociodemographic and behavioural factors±pandemic stressors | Vaccination was associated with longer cycles after vaccination (0–6 months: OR 1.67 (95% CI 1.05 to 2.64); 7–9 months: OR 1.43 (95% CI 0.96 to 2.14); >9 months: OR 1.41 (95% CI 0.91 to 2.18)) and among those whose cycles were short, long or irregular before vaccination (OR 2.82 (95% CI 1.51 to 5.27); OR 1.10 (95% CI 0.68 to 1.77) for those with normal length, regular cycles before vaccination). mRNA and adenovirus-vectored vaccines were both associated with this change | Low |
Wesselink22 | 2023 | Prospective cohort study | US and Canada | 1137 | 21–45 years | 6/2021–8/2022 | Moderna, Pfizer, Janssen | Cycle regularity, cycle length, bleed length, heaviness of bleed and menstrual pain | Sociodemographic, lifestyle, medical and reproductive factors | Participants had 1.1-day longer cycles after the first dose of vaccine (95 % CI 0.4 to 1.9) and 1.3-day longer cycles after the second dose (95 % CI 0.2 to 2.5). Associations were attenuated at the second cycle post-vaccination. There was little association with cycle regularity, days of flow, menstrual volume or pain | Low |
AMH, anti-Müllerian hormone; BMI, body mass index; CI, confidence interval; HR, hazard ratio; IQR, interquartile range; mRNA, messenger RNA; OR, odds ratio; UK, United Kingdom; US, United States; β, mean difference.