Peer Support in Online Women's Health Communities: Mixed Methods Formative Analysis of Reddit Discourse.

Background: Stigmatized women's health issues, such as polycystic ovary syndrome (PCOS) and endometriosis, are often marginalized or dismissed in traditional clinical settings. This drives individuals to seek peer support in anonymous online communities such as Reddit. While these digital platforms host critical discussions, they are often designed as static information repositories, failing to account for the complex emotional, temporal, and cultural dynamics that shape users' support needs. There is a disconnect between the lived experiences of users-particularly feelings of clinical dismissal and the need for culturally specific advice-and the design of the sociotechnical systems they rely on. Objective: This study aimed to deconstruct support practices in online women's health forums to provide a formative basis for designing more responsive digital health systems. We analyzed the intersections of discussion topics, emotional expression, temporal shifts (specifically the impact of the COVID-19 pandemic), and culturally situated discourse to identify unmet user needs and effective peer-support patterns. Methods: We conducted a large-scale, mixed-methods analysis of 4995 posts and 460,317 comments from 5 major women's health subreddits (r/WomensHealth, r/TwoXChromosomes, r/BirthControl, r/Endometriosis, and r/PCOS). Computational methods included Latent Dirichlet Allocation for topic modeling, Valence Aware Dictionary for Sentiment Reasoning for sentiment analysis, and the NRC Emotion Lexicon for granular emotion classification. We segmented the data into pre-, during-, and post-COVID-19 periods to analyze temporal shifts. This quantitative analysis was complemented by a 2-phase qualitative thematic analysis to identify and characterize engagement patterns within 147 validated culturally situated threads. Results: Our analysis revealed that the most prevalent and emotionally negative topic was "Pain & Doctor Visits," which was uniquely characterized by high levels of fear and sadness linked to systemic clinical dismissal. The COVID-19 pandemic triggered a significant topical "turn inward," with discussions shifting away from social or political issues and toward somatic concerns (eg, "PCOS" "Pain & Doctor Visits"). Paradoxically, this period saw a simultaneous rise in both negative emotions (eg, fear and sadness) and expressions of community trust. Critically, our qualitative analysis of culturally situated discourse uncovered a consistent three-stage "playbook" for effective support: (1) Affirmation to establish psychological safety and validate cultural experiences; (2) Information Scaffolding to provide actionable, culturally tailored advice; and (3) Intercultural Bridging to facilitate community-wide learning and empathy. Conclusions: Online health forums operate as essential, resilient sociotechnical infrastructures that actively compensate for failures and gaps in formal health care. The "Affirmation-Scaffolding-Bridging" model identified in our research provides a clear, formative framework for designing future digital health interventions. These findings can guide the development of new platforms that are emotionally aware, culturally responsive, and adaptive to user needs and external crises.