A process to form an ethylene-based polymer comprising, in polymerized form, ethylene and at least one acid comonomer, said process comprising polymerizing a reaction mixture comprising the ethylene and the acid comonomer, in a reactor configuration comprising at least one Secondary compressor, at least one pressurization device, and at least one reactor selected from the following: at least one autoclave reactor, at least one tubular reactor, or a combination thereof; and wherein the reaction mixture is polymerized in the presence of at least one free-radical initiator, and at a pressure of at least 1000 Bar; and wherein at least a portion of a comonomer composition comprising at least a portion of the acid comonomer used in the polymerization, is compressed, to form a compressed comonomer composition, in the pressurization device, up to a discharge pressure ranging from 1000 Bar to 4000 Bar, and at a discharge temperature (DT) from 10 C to 100 C; and wherein the compressed comonomer composition bypasses the Secondary compressor, and is fed, downstream from the Secondary compressor, into the reactor, and/or into one or more feed streams to the reactor.