Language-based acculturation is linked with reproductive autonomy among Oregon Mexican-origin Latinas.

OBJECTIVES: We test whether the level of acculturation is associated with reproductive autonomy among Mexican-origin Latinas in Oregon. STUDY DESIGN: This was a cross-sectional study that used validated reproductive autonomy and language-based acculturation scales and sociodemographic information. We compared maximum reproductive autonomy score, overall and for each subscale (decision-making, freedom from coercion, and communication), by acculturation group. We developed a multivariable logistic regression model adjusted for age, education, and regular income source. RESULTS: Our sample included 434 respondents: 70.7% low, 26.7% bicultural, and 2.5% in the high acculturation group. A higher unadjusted proportion of women in the bicultural/high acculturation group than the low acculturation group had maximum reproductive autonomy scores (13.4% compared with 3.9%; p < 0.001). In adjusted analyses, women in the high/bicultural acculturation group had significantly higher odds of reporting a maximum reproductive autonomy score (adjusted odds ratio = 2.55, 95% CI: 1.08-5.98). CONCLUSIONS: Language-based acculturation was positively associated with reproductive autonomy among a community-dwelling sample of Mexican-origin Latinas in Oregon.

"That is when I understood everything": Ideological trajectories of pro-choice female doctors in Mexico.

OBJECTIVES: There is little evidence about how physicians become abortion clinicians or advocates. We describe the ideological trajectories of pro-choice female Mexican doctors and the factors that made them pro-choice. STUDY DESIGN: In this qualitative study, we conducted semistructured interviews with members of the Mexican Network of Female Pro-choice Physicians. Participants came from eight diverse states. We used a feminist epistemology approach and analyzed data using inductive coding as well as a priori categories (becoming pro-choice, trajectories, and training). RESULTS: We included 24 female pro-choice physicians. We identified five intersecting factors that influenced becoming pro-choice: feminism, personal experiences, confrontation with the inequalities and violence that women experience, role models, and routine exposure to abortion care. Participants described three ideological trajectories: being pro-choice before studying medicine, not having a specific opinion, and changing from "pro-life" to "pro-choice." Participants described the absence of abortion training in medical schools, stigmatizing training, and the use of alternative training sources. CONCLUSIONS: In the absence of training on abortion during medical education, a combination of intersecting personal as well as work-related experience may turn doctors into pro-choice abortion clinicians and/or advocates. The findings of this study may be used to develop comprehensive medical curricula as well as strategies directed at doctors who have never received training on abortion care, such as promoting interactions with nonmedical abortion providers, education on inequalities and violence against women, moving beyond public health to a human rights and gender perspective, and exposure to routine safe abortion care. IMPLICATIONS: Mexican female doctors become pro-choice clinicians who provide abortion care and/or advocates in spite of their medical education.

Targeted hypermutation of putative antigen sensors in multicellular bacteria.

Diversity-generating retroelements (DGRs) are used by bacteria, archaea, and viruses as a targeted mutagenesis tool. Through error-prone reverse transcription, DGRs introduce random mutations at specific genomic loci, enabling rapid evolution of these targeted genes. However, the function and benefits of DGR-diversified proteins in cellular hosts remain elusive. We find that 82% of DGRs from one of the major monophyletic lineages of DGR reverse transcriptases are encoded by multicellular bacteria, which often have two or more DGR loci in their genomes. Using the multicellular purple sulfur bacterium Thiohalocapsa sp. PB-PSB1 as an example, we characterized nine distinct DGR loci capable of generating 10282 different combinations of target proteins. With environmental metagenomes from individual Thiohalocapsa aggregates, we show that most of PB-PSB1's DGR target genes are diversified across its biogeographic range, with spatial heterogeneity in the diversity of each locus. In Thiohalocapsa PB-PSB1 and other bacteria hosting this lineage of cellular DGRs, the diversified target genes are associated with NACHT-domain anti-phage defenses and putative ternary conflict systems previously shown to be enriched in multicellular bacteria. We propose that these DGR-diversified targets act as antigen sensors that confer a form of adaptive immunity to their multicellular consortia, though this remains to be experimentally tested. These findings could have implications for understanding the evolution of multicellularity, as the NACHT-domain anti-phage systems and ternary systems share both domain homology and conceptual similarities with the innate immune and programmed cell death pathways of plants and metazoans.

Timing of Coronavirus Disease 2019 (COVID-19) Vaccination and Effects on Menstrual Cycle Changes.

OBJECTIVE: To assess whether menstrual cycle timing (follicular or luteal phase) of coronavirus disease 2019 (COVID-19) vaccine administration is associated with cycle length changes. METHODS: We used prospectively collected (2021-2022) menstrual cycle tracking data from 19,497 reproductive-aged users of the application "Natural Cycles." We identified whether vaccine was delivered in the follicular or luteal phase and also included an unvaccinated control group. Our primary outcome was the adjusted within-individual change in cycle length (in days) from the average of the three menstrual cycles before the first vaccination cycle (individuals in the unvaccinated control group were assigned a notional vaccine date). We also assessed cycle length changes in the second vaccination cycle and whether a clinically significant change in cycle length (8 days or more) occurred in either cycle. RESULTS: Most individuals were younger than age 35 years (80.1%) and from North America (28.6%), continental Europe (33.5%), or the United Kingdom (31.7%). In the vaccinated group, the majority received an mRNA vaccine (63.8% of the full sample). Individuals vaccinated in the follicular phase experienced an average 1-day longer adjusted cycle length with a first or second dose of COVID-19 vaccine compared with their prevaccination average (first dose: 1.00 day [98.75% CI, 0.88-1.13], second dose: 1.11 days [98.75% CI, 0.93-1.29]); those vaccinated in the luteal phase and those in the unvaccinated control group experienced no change in cycle length (respectively, first dose: -0.09 days [98.75% CI, -0.26 to 0.07], second dose: 0.06 days [98.75% CI, -0.16 to 0.29], unvaccinated notional first dose: 0.08 days [98.75% CI, -0.10 to 0.27], second dose: 0.17 days [98.75% CI, -0.04 to 0.38]). Those vaccinated during the follicular phase were also more likely to experience a clinically significant change in cycle length (8 days or more; first dose: 6.8%) than those vaccinated in the luteal phase or unvaccinated (3.3% and 5.0%, respectively; P <.001). CONCLUSION: COVID-19 vaccine-related cycle length increases are associated with receipt of vaccination in the first half of the menstrual cycle (follicular phase).

Prenatal care utilization and perinatal outcomes among pregnant adolescents in Mexico, 2008-2019.

OBJECTIVE: To describe utilization of prenatal care and outcomes of low birth weight and preterm birth among adolescent births in Mexico. METHODS: We used birth certificate data and included live births to individuals 10-24 years, 2008-2019. Our outcomes were binary measures of adequate prenatal care, low birth weight, and preterm birth. We compared adolescents (10-14 years, 15-16, and 17-19) to those 20-24 years. We included individual-, clinical-, and municipality-level variables, used multivariable logistic regression, and calculated adjusted predicted probabilities. We also tested whether receipt of prenatal care moderated the relationship of age with preterm birth and low birth weight. RESULTS: We included a total of 12 106 710 births to women 10-24 years. The adjusted predicted probability of adequate prenatal care increased with age: 56.07% (95% CI 55.82-56.31%) adjusted probability among adolescents 10-14 years compared with 65.51% (95% CI 65.48%-65.55%) among individuals 20-24 years. Receipt of adequate prenatal care in part mitigated disparities in preterm birth and low birthweight across all age groups: 7.30% (95% CI 7.17%-7.43%) adjusted probability of delivering a preterm infant among those 10-14 years who received adequate prenatal care compared with 9.37% (95% CI 9.20%-9.53%) among those 10-14 years without adequate prenatal care. CONCLUSION: In Mexico, adolescent pregnancies are associated with inadequate prenatal care as well as higher odds of preterm delivery and low birth weight. Youngest adolescents (10-14 years) have the highest probability of adverse outcomes. Adequate prenatal care may help partially mitigate disparities in poor perinatal outcomes.

A novel conjugative transposon carrying an autonomously amplified plasmid.

Tetracyclines serve as broad-spectrum antibiotics to treat bacterial infections. The discovery of new tetracycline resistance genes has led to new questions about the underlying mechanisms of resistance, gene transfer, and their relevance to human health. We tracked changes in the abundance of a 55-kbp conjugative transposon (CTn214) carrying tetQ, a tetracycline resistance gene, within a Bacteroides fragilis metagenome-assembled genome derived from shotgun sequencing of microbial DNA extracted from the ileal pouch of a patient with ulcerative colitis. The mapping of metagenomic reads to CTn214 revealed the multi-copy nature of a 17,044-nt region containing tetQ in samples collected during inflammation and uninflamed visits. B. fragilis cultivars isolated from the same patient during periods of inflammation harbored CTn214 integrated into the chromosome or both a circular, multi-copy, extrachromosomal region of the CTn214 containing tetQ and the corresponding integrated form. The tetracycline-dependent mechanism for the transmission of CTn214 is nearly identical to a common conjugative transposon found in the genome of B. fragilis (CTnDOT), but the autonomously amplified nature of a circular 17,044-nt region of CTn214 that codes for tetQ and the integration of the same sequence in the linear chromosome within the same cell is a novel observation. Genome and transcriptome sequencing of B. fragilis cultivars grown under different concentrations of tetracycline and ciprofloxacin indicates that tetQ in strains containing the circular form remains actively expressed regardless of treatment, while the expression of tetQ in strains containing the linear form increases only in the presence of tetracycline.IMPORTANCEThe exchange of antibiotic production and resistance genes between microorganisms can lead to the emergence of new pathogens. In this study, short-read mapping of metagenomic samples taken over time from the illeal pouch of a patient with ulcerative colitis to a Bacteroides fragilis metagenome-assembled genome revealed two distinct genomic arrangements of a novel conjugative transposon, CTn214, that encodes tetracycline resistance. The autonomous amplification of a plasmid-like circular form from CTn214 that includes tetQ potentially provides consistent ribosome protection against tetracycline. This mode of antibiotic resistance offers a novel mechanism for understanding the emergence of pathobionts like B. fragilis and their persistence for extended periods of time in patients with inflammatory bowel disease.

Client-reported quality of facility-managed medication abortion compared with pharmacy-sourced self-managed abortion in Bangladesh.

OBJECTIVE: We used the newly developed Abortion Care Quality Tool (ACQTool) to compare client-reported quality of medication abortion care by source (facility-managed vs pharmacy-sourced self-managed abortion (SMA)) in Bangladesh. METHODS: We leveraged exit and 30-day follow-up surveys collected to develop and validate the ACQTool collected at nongovernmental organisation (NGO)-supported or -operated facilities in the public and private sector and pharmacies from three districts in Bangladesh. We used bivariate statistics to compare 18 client-reported quality indicators grouped in six domains and eight abortion outcomes, by source (facility vs pharmacy). We used multivariable logistic regression to identify factors associated with selected quality indicators and outcomes (abortion affordability, information provision, and knowing what to do for an adverse event), controlling for client sociodemographic characteristics. RESULTS: Of 550 abortion clients, 146 (26.5%) received a facility-managed medication abortion and 404 (73.5%) had a pharmacy-sourced SMA. Clients reported higher quality in facilities for five indicators, and higher in pharmacies for two indicators; the remaining 11 indicators were not different by source. Compared with facility-based clients, pharmacy clients had higher odds of reporting that the cost of abortion was affordable (adjusted odds ratio (aOR) 3.55; 95% CI 2.27 to 5.58) but lower odds of reporting high information provision (aOR 0.14; 95% CI 0.09 to 0.23). Seven of eight abortion outcomes showed no differences; pharmacy clients had lower odds of knowing what to do if an adverse event occurred (aOR 0.45; 95% CI 0.23 to 0.82). CONCLUSIONS: In Bangladesh, there is no difference in client-reported quality of medication abortion care between health facilities and pharmacies for the majority of quality and outcome indicators. However, information provision and preparedness were higher quality at facilities, while pharmacies were more affordable.

Association between COVID-19 and vaccination on menstrual cycle.

OBJECTIVE: 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). METHODS: A cross-sectional study at the University of Campinas, Brazil using Google questionnaire applied from December 2021 through February 2022, disseminated through snowball technique. Participants responded about characteristics of their menstrual cycle before the pandemic and before COVID-19 vaccination, and then about characteristics of their cycle 3 months after infection with SARS-CoV-2 and 3 months after vaccination. Our primary outcome was a binary indicator of changes in the menstrual cycle. We used multivariate regression analysis to identify factors associated with menstrual changes. 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. CONCLUSION: Our results corroborated the stability of the menstrual cycle after having COVID-19 or COVID-19 vaccination; however, there is a potential relationship between menstrual changes and socioeconomic factors as well as contraceptive use.

Viruses and Cajal Bodies: A Critical Cellular Target in Virus Infection?

Nuclear bodies (NBs) are dynamic structures present in eukaryotic cell nuclei. They are not bounded by membranes and are often considered biomolecular condensates, defined structurally and functionally by the localisation of core components. Nuclear architecture can be reorganised during normal cellular processes such as the cell cycle as well as in response to cellular stress. Many plant and animal viruses target their proteins to NBs, in some cases triggering their structural disruption and redistribution. Although not all such interactions have been well characterised, subversion of NBs and their functions may form a key part of the life cycle of eukaryotic viruses that require the nucleus for their replication. This review will focus on Cajal bodies (CBs) and the viruses that target them. Since CBs are dynamic structures, other NBs (principally nucleoli and promyelocytic leukaemia, PML and bodies), whose components interact with CBs, will also be considered. As well as providing important insights into key virus-host cell interactions, studies on Cajal and associated NBs may identify novel cellular targets for development of antiviral compounds.

Structural Requirements for Reverse Transcription by a Diversity-generating Retroelement.

Diversity-generating retroelements (DGRs), which are pervasive among microbes, create massive protein sequence variation through reverse transcription of a protein-coding RNA template coupled to frequent misincorporation at template adenines. For cDNA synthesis, the template must be surrounded by up- and downstream sequences. Cryo-EM revealed that this longer RNA formed an integral ribonucleoprotein (RNP) with the DGR reverse transcriptase bRT and associated protein Avd. The downstream, noncoding (nc) RNA formed stem-loops enveloping bRT and laying over barrel-shaped Avd, and duplexes with the upstream and template RNA. These RNA structural elements were required for reverse transcription, and several were conserved in DGRs from distant taxa. Multiple RNP conformations were visualized, and no large structural rearrangements occurred when adenine replaced guanine as the template base, suggesting energetics govern misincorporation at adenines. Our results explain how the downstream ncRNA primes cDNA synthesis, promotes processivity, terminates polymerization, and stringently limits mutagenesis to DGR variable proteins.

Diversity at single nucleotide to pangenome scales among sulfur cycling bacteria in salt marshes.

IMPORTANCE: Salt marshes are known for their significant carbon storage capacity, and sulfur cycling is closely linked with the ecosystem-scale carbon cycling in these ecosystems. Sulfate reducers are key for the decomposition of organic matter, and sulfur oxidizers remove toxic sulfide, supporting the productivity of marsh plants. To date, the complexity of coastal environments, heterogeneity of the rhizosphere, high microbial diversity, and uncultured majority hindered our understanding of the genomic diversity of sulfur-cycling microbes in salt marshes. Here, we use comparative genomics to overcome these challenges and provide an in-depth characterization of sulfur-cycling microbial diversity in salt marshes. We characterize communities across distinct sites and plant species and uncover extensive genomic diversity at the taxon level and specific genomic features present in MAGs affiliated with uncultivated sulfur-cycling lineages. Our work provides insights into the partnerships in salt marshes and a roadmap for multiscale analyses of diversity in complex biological systems.

The Cajal body protein p80-coilin forms a complex with the adenovirus L4-22K protein and facilitates the nuclear export of adenovirus mRNA.

IMPORTANCE: The architecture of sub-nuclear structures of eucaryotic cells is often changed during the infectious cycle of many animal and plant viruses. Cajal bodies (CBs) form a major sub-nuclear structure whose functions may include the regulation of cellular RNA metabolism. During the lifecycle of human adenovirus 5 (Ad5), CBs are reorganized from their spherical-like structure into smaller clusters termed microfoci. The mechanism of this reorganization and its significance for virus replication has yet to be established. Here we show that the major CB protein, p80-coilin, facilitates the nuclear export of Ad5 transcripts. Depletion of p80-coilin by RNA interference led to lowered levels of viral proteins and infectious virus. p80-coilin was found to form a complex with the viral L4-22K protein in Ad5-infected cells and in some reorganized microfoci. These findings assign a new role for p80-coilin as a potential regulator of infection by a human DNA virus.

Awareness of the public charge, confidence in knowledge, and the use of public healthcare programs among Mexican-origin Oregon Latino/as.

OBJECTIVE: We describe awareness about the modified "public charge" rule among Oregon's Mexican-origin Latino/a population and whether concerns about the rule influenced disenrollment from state-funded programs, which do not fall under the public charge. METHODS: We conducted a cross-sectional survey of adults (ages 18-59) recruited at the Mexican consulate and living in the state of Oregon. Our outcomes were awareness (of the public charge, source of knowledge, and confidence in knowledge of the public charge) and disenrolling self or family members from state-funded public healthcare programs due to concerns about the rule. We described outcomes and used logistic regression and calculated adjusted probabilities to identify factors associated with awareness of the public charge. RESULTS: Of 498 Latino/a respondents, 48% reported awareness of the public charge. Among those who knew about the public charge, 14.6% had disenrolled themselves or family members from public healthcare programs and 12.1% were hesitant to seek care due to concerns about the public charge. Younger respondents had a lower adjusted probability of awareness of the public charge (18-24 years: 15.6% (95% CI 3.1-28.2); 30-39 years 54.9% (95% CI 47.7-62.0). Higher education was associated with a higher adjusted probability of awareness of the public charge; ability to speak English was not associated with awareness of the public charge. CONCLUSION: Our study reveals limited awareness about the public charge among Mexican-origin Oregon Latino/as. Outreach and advocacy are essential to ensure Latino/as know their rights to access available state-funded healthcare programs.

Landscape of Pregnancy Care in US Community Health Centers.

PURPOSE: Community health centers (CHCs) provide critical health care access for people who experience high risks during and after pregnancy, however it is unclear to what extent they provide prenatal care. This study seeks to describe clinic and patient characteristics associated with longitudinal prenatal care delivery in CHC settings. METHODS: This retrospective cohort study utilized electronic health record (EHR) data from the Accelerating Data Value Across a National Community Health Center Network (ADVANCE) between 2018 to 2019 to describe prenatal care provision among CHCs (n = 408), and pregnant CHC patients (n = 28,578) and compared characteristics of patients who received longitudinal prenatal care at CHCs versus those who did not. RESULTS: 41% of CHCs provided longitudinal prenatal care; these CHCs were more likely to be larger, have multidisciplinary teams, and serve higher proportions of nonwhite or non-English speaking patients. Patients who received longitudinal prenatal care at CHCs were racially and ethnically diverse and many had comorbidities. Patients who received longitudinal prenatal care at CHCs (compared with pregnant patients who did not) were more likely to be white or Latinx and more likely to have non-English language preference. CONCLUSIONS: Many CHCs in this national network provide prenatal care and serve pregnant patients at high risk of pregnancy-related complications, including people of color, those with low income, and those with comorbidities. CHCs provide critical access to care for vulnerable populations and will be an important partner in work addressing inequities in maternal morbidity and mortality.

Contraceptive Method Switching and Long-Acting Reversible Contraception Removal in U.S. Safety Net Clinics, 2016-2021.

OBJECTIVE: To describe patterns of contraceptive method switching and long-acting reversible contraception (LARC) removal in a large network of community health centers. METHODS: We conducted a retrospective cohort study using individual-level electronic health record data from 489 clinics in 20 states from 2016 to 2021. We used logistic regression models, including individual-, clinic-, and state-level covariates, to calculate adjusted odds ratios and predicted probabilities of any observed contraceptive method switching and LARC removal among those with baseline incident LARC, both over 4-year time periods. RESULTS: Among 151,786 patients with 513,753 contraceptive encounters, 22.1% switched to another method at least once over the 4-year observation period, and switching patterns were varied. In patients with baseline LARC, the adjusted predicted probability of switching was 19.0% (95% CI 18.0-20.0%) compared with patients with baseline moderately effective methods (16.2%, 95% CI 15.1-17.3%). The adjusted predicted probability of switching was highest among the youngest group (28.6%, 95% CI 25.8-31.6% in patients aged 12-14 years) and decreased in a dose-response relationship by age to 8.4% (95% CI 7.4-9.4%) among patients aged 45-49 years. Latina and Black race and ethnicity, public or no insurance, and baseline Title X clinic status were all associated with higher odds of switching at least once. Among baseline LARC users, 19.4% had a removal (to switch or discontinue) within 1 year and 30.1% within 4 years; 97.6% of clinics that provided LARC also had evidence of a removal. CONCLUSION: Community health centers provide access to method switching and LARC removal. Contraceptive switching and LARC removal are common, and clinicians should normalize switching and LARC removal among patients.

Public perceptions of abortion complications.

BACKGROUND: Misinformation contributes to the perception that abortion has substantial health risks, despite the known safety of medication and aspiration abortion. We lack detailed information about which health risks the public believes are most likely. OBJECTIVE: This study aimed to describe public perception of short- and long-term risks of abortion. STUDY DESIGN: We conducted a cross-sectional survey of US residents aged ≥18 years using Amazon Mechanical Turk (MTurk). We collected information regarding participant demographics, reproductive history, political views, and position on abortion restrictions. We provided participants with a list of 9 short-term and 15 long-term possible complications and asked them to indicate whether they occurred never (0%), very rarely (<1%), rarely (1%-5%), occasionally (5%-20%), or frequently (>20%) following abortion. We used descriptive statistics to understand our population demographics and to capture the perceived incidence of all complications. We created a binary indicator of answering all risk estimates incorrectly vs at least 1 estimate correctly, separately for all long-term possible complications, and the 2 short-term risks of infection and bleeding. We determined the proportion of individuals who responded incorrectly to all questions in each category and used multivariable logistic regression to identify factors associated with incorrect perceptions about the risks of abortion. RESULTS: For all listed complications, participant (N=1057) estimates of risk were higher than the known incidence. For both short-term risks of bleeding and infection, over 40% of participants reported that these outcomes occur occasionally or frequently. Similarly, for both long-term risks of depression and anxiety, over 60% of respondents reported that these outcomes occur occasionally or frequently after abortion. Participants reported that possible complications known to not be associated with abortion, including hair loss, future pregnancy complications, breast cancer, and cosmetic disfigurement, occurred at least rarely. Nearly one-quarter of participants responded that death occurs occasionally or frequently (in over 5% of abortions), and 79% of participants responded that breast cancer can result from abortion. One-quarter (24.9%) of participants incorrectly overestimated both short-term outcomes of infection and bleeding, whereas 19.5% answered all long-term complication questions incorrectly, including outcomes that never occur. On multivariable analyses, we identified that the participants most likely to incorrectly identify risks of abortion identified as Asian or Black race/ethnicity, were from rural communities, or believed that abortion should have more legal restrictions. CONCLUSION: The public perceives abortion to be much riskier than it actually is. This information can be used to develop targeted clinical and public health efforts to disseminate the true risks of abortion.

Impact of coronavirus disease 2019 (COVID-19) vaccination on menstrual bleeding quantity: An observational cohort study.

OBJECTIVE: To assess whether coronavirus disease 2019 (COVID-19) vaccination impacts menstrual bleeding quantity. DESIGN: Retrospective cohort. SETTING: Five global regions. POPULATION: Vaccinated and unvaccinated individuals with regular menstrual cycles using the digital fertility-awareness application Natural Cycles°. METHODS: We used prospectively collected menstrual cycle data, multivariable longitudinal Poisson generalised estimating equation (GEE) models and multivariable multinomial logistic regression models to calculate the adjusted difference between vaccination groups. All regression models were adjusted for confounding factors. MAIN OUTCOME MEASURES: The mean number of heavy bleeding days (fewer, no change or more) and changes in bleeding quantity (less, no change or more) at three time points (first dose, second dose and post-exposure menses). RESULTS: We included 9555 individuals (7401 vaccinated and 2154 unvaccinated). About two-thirds of individuals reported no change in the number of heavy bleeding days, regardless of vaccination status. After adjusting for confounding factors, there were no significant differences in the number of heavy bleeding days by vaccination status. A larger proportion of vaccinated individuals experienced an increase in total bleeding quantity (34.5% unvaccinated, 38.4% vaccinated; adjusted difference 4.0%, 99.2% CI 0.7%-7.2%). This translates to an estimated 40 additional people per 1000 individuals with normal menstrual cycles who experience a greater total bleeding quantity following the first vaccine dose' suffice. Differences resolved in the cycle post-exposure. CONCLUSIONS: A small increase in the probability of greater total bleeding quantity occurred following the first COVID-19 vaccine dose, which resolved in the cycle after the post-vaccination cycle. The total number of heavy bleeding days did not differ by vaccination status. Our findings can reassure the public that any changes are small and transient.