An Open-Label, Dose Finding Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Subcutaneous CBP-4888 in Hospitalized Participants with Preterm Preeclampsia Receiving Standard of Care, Expectant Management. The study will follow a single ascending dose design, with up to 60 participants enrolled across 6 dose level groups. For each of the planned six dose levels, all 4 participants will receive a single SC injection dose of IP (CBP-4888) + standard of care (SOC)/Expectant Management + additional safety surveillance for the mother and neonate through delivery and for 42 days (+14 days) after delivery. Infants will be followed for up to 24 months.