A process for producing a water-absorbing polymer composition, comprising the process steps of (i) mixing (α1) 0.1 to 99.999% by weight of ethylenically unsaturated monomers containing acid groups or salts thereof (α2) 0 to 70% by weight of polymerized, ethylenically unsaturated monomers copolymerizable with (α1), (α3) 0.001 to 10% by weight of one or more crosslinkers, (α4) 0 to 30% by weight of water-soluble polymers, and (α5) 0 to 20% by weight of one or more assistants, where the sum of their weights (α1) to (α5) is 100% by weight, (ii) free-radical polymerization with crosslinking to form a water-insoluble aqueous untreated hydrogel polymer, and surface postcrosslinking the ground hydrogel polymer wherein blowing agents having a particle size of 100 μm to 900 μm are added to the aqueous monomer solution prior to the addition of the initiator and the start of the free-radical polymerization.
