Modified Project Summary/Abstract Section Historically, research on sexual and reproductive health (SRH) and pregnancy related topics has excluded or misclassified some people. This has led to a lack of pregnancy-related research among priority populations, as well as misclassification and bias in existing state and national datasets. The dearth of representative data has meant, critically, that healthcare providers do not have adequate evidence upon which to rely to ensure that the pregnancy-related needs of all their patients are met within existing healthcare services--thereby contributing to lower quality care and disparities. Consequently, this study aims to test methods of improving the research participation, retention, and quality of collected sexual and reproductive health data in the United States. The specific aims include: (1) recruit a large, varied sample of people from across the United States, (2) collect longitudinal data on core pregnancy-related outcomes from this more complete sample of participants, and (3) improve retention and data quality in research as compared to standard methods. To achieve these aims, we will implement a four-arm, parallel design assessment that randomizes participants to receipt of zero, one, or two novel survey features in their online survey: an anatomical organ inventory for screening into survey logic, and/or customizable survey language to personalize their survey experience. The control group will be randomized to common data element validated questions and use of standard medical terms. The research will address challenges encountered in previous research and will contribute to the evidence around best practices for data collection with other populations historically characterized as “hard-to-reach” in the context of public health research and clinical care. The evidence generated by this study could have wide-ranging impacts—including refined determination of research and clinical care eligibility, improved research participation, and better healthcare screening and treatment for all. Beyond advancing the evidence-base, the novel survey methodologies tested in this study could be applied broadly to advance public health research approaches and improve the accuracy and relevance of data collection with a wide range of populations and topics.