<h3>Objective:</h3> To assess the pregnancy and infant safety of ocrelizumab after maternal use in the 6 months before or during pregnancy in the setting of routine healthcare. <h3>Background:</h3> Ocrelizumab is a recombinant, humanized, monoclonal immunoglobulin G1 antibody that selectively targets CD20<sup>+</sup> B cells. Immunoglobulins are known to cross the placental barrier, and women of childbearing age should use contraception while receiving ocrelizumab and for 6 months after the last infusion. Therefore, knowledge of how ocrelizumab exposure affects pregnancy and infant outcomes in humans is limited. <h3>Design/Methods:</h3> This study will use multiple sources of data collected prospectively, including existing population-based healthcare registries from Denmark and three United States claims databases. Ocrelizumab-exposed pregnancies in women with multiple sclerosis (MS) will be compared with: (1) pregnancies in women with MS without ocrelizumab exposure; and (2) pregnancies in women without MS and no ocrelizumab exposure. The frequency of adverse pregnancy outcomes (including spontaneous abortions, stillbirths, elective abortions, preterm births, C-sections and urinary and other infections) and adverse infant outcomes (including major congenital malformations, small for gestational age, and adverse effects on immune system development) will be estimated and compared across matched cohorts (validation of selected outcomes may be conducted). Analyses will be conducted within each data source separately and subsequently pooled using meta-analytic techniques. <h3>Results:</h3> The observation period will start when ocrelizumab is first prescribed within one of the participating data sources (Q2 2017), and the study will be completed in Q1 2023. <h3>Conclusions:</h3> This study will complement the planned Ocrelizumab Pregnancy Registry and address some known limitations of registries (e.g. slow enrollment, loss to follow-up), while generating important information on pregnancy and fetal outcomes following exposure to ocrelizumab. This information will be useful in guiding discussions between healthcare providers and women who may have been exposed to ocrelizumab before or during pregnancy. <b>Study Supported by:</b> Sponsored by F. Hoffmann-La Roche Ltd; writing and editorial assistance was provided by Health Interactions, USA and Articulate Science, UK. <b>Disclosure:</b> Dr. Margulis has received research support from Andrea V Margulis is an employee of RTI Health Solutions, which received funding from F. Hoffmann-La Roche Ltd. to conduct this research. The contract between RTI Health Solutions and Roche includes independent publication rights. RTI International, of w. Dr. Andrews has received research support from Elizabeth B Andrews is an employee of RTI Health Solutions, which received funding from F. Hoffmann-La Roche Ltd. to conduct this research. The contract between RTI Health Solutions and Roche includes independent publication rights. RTI International, of. Dr. Hern[aacute]ndez-Diaz has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with SHD was the epidemiologist for the North American Antiepileptic Drugs pregnancy registry and advisor for the Antipsychotics Pregnancy Registry, which are non-profit, but funded my multiple companies. Dr. Hern[aacute]ndez-Diaz has received research support from SHD participates as investigator in projects funded by Pfizer, GSK, and Lilly. Dr. Magyari has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen, Sanofi, Teva, Roche, Novartis, Merck. Dr. Magyari has received research support from received support for congress participation from Biogen, Genzyme, Teva, Roche. Dr. Rivero-Ferrer has received research support from Elena Rivero-Ferrer is an employee of RTI Health Solutions, which received funding from F. Hoffmann-La Roche Ltd. to conduct this research. The contract between RTI Health Solutions and Roche includes independent publication rights. RTI International, of. Dr. Bader-Weder has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Silvia Bader-Weder is an employee and shareholder of F. Hoffmann-La Roche Ltd. Dr. Evershed has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Yes - employment at Roche Products Ltd and shareholder of F. Hoffman-La Roche Ltd. Dr. Garas has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with M Garas is an employee and shareholder of F. Hoffmann-La Roche Ltd. Dr. Wang has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Qing Wang is an employee of F. Hoffmann-La Roche Ltd. Dr. Wormser has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with F. Hoffmann-La Roche Ltd.