Plain Language Summary of Publication: Design of the Phase 3 FREESIA-1 and FREESIA-3 Trials of Nipocalimab in Fetal and Neonatal Alloimmune Thrombocytopenia.

This article is a plain language summary of publication (PLSP) of the following articles: "Design of a Phase 3, Multicenter, Randomized, Placebo-Controlled, Double-Blind Study of Nipocalimab in Pregnancies at Risk for Fetal and Neonatal Alloimmune Thrombocytopenia (FREESIA-1)" by Tiller et al published in <i>American Journal of Perinatology</i> on July 28, 2025 (doi:10.1055/a-2666-5642) and "Design of a Phase 3, Multicenter, Randomized, Open-Label Study of Nipocalimab or IVIG and Prednisone in Pregnancies at Risk for Fetal and Neonatal Alloimmune Thrombocytopenia (FREESIA-3)" by Bussel et al published in <i>American Journal of Perinatology</i> on November 25, 2025 (doi: 10.1055/a-2753-9323). This PLSP describes the design of the phase 3, placebo-controlled FREESIA-1 and open-label FREESIA-3 trials, which will help researchers understand if nipocalimab, an investigational treatment, can be used to safely treat pregnant individuals who are at risk for fetal and neonatal alloimmune thrombocytopenia (FNAIT). This PLSP will help the general public, including those affected by FNAIT, and health care professionals understand the two studies. It provides information on the eligibility criteria, study design, treatments, and outcomes of interest. An infographic summary of this article is available in the Supplementary Material (available in the online version only).