The invention relates to a process for producing a water-absorbing polymer composition, comprising the process steps of (i) mixing ( &agr; 1) 0.1 to 99.999% by weight, preferably 20 to 98.99% by weight and more preferably 30 to 98.95% by weight of polymerized, ethylenically unsaturated monomers containing acid groups or salts thereof or polymerized, ethylenically unsaturated monomers including a protonated or quaternized nitrogen, or mixtures thereof, particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acid groups, preferably acrylic acid, ( &agr; 2) 0 to 70% by weight, preferably 1 to 60% by weight and more preferably 1 to 40% by weight of polymerized, ethylenically unsaturated monomers copolymerizable with ( &agr; 1), ( &agr; 3) 0.001 to 10% by weight, preferably 0.01 to 7% by weight and more preferably 0.05 to 5% by weight of one or more crosslinkers, ( &agr; 4) 0 to 30% by weight, preferably 1 to 20% by weight and more preferably 5 to 10% by weight of water-soluble polymers, and ( &agr; 5) 0 to 20% by weight, preferably 0.01 to 7% by weight and more preferably 0.05 to 5% by weight of one or more assistants, where the sum of their weights ( &agr; 1) to ( &agr; 5) is 100% by weight, (ii) free-radical polymerization with crosslinking to form a water-insoluble aqueous untreated hydrogel polymer, (iii) comminuting and drying the hydrogel polymer, (iv) optionally grinding and sieving the water-absorbing polymer, (v) surface postcrosslinking the ground hydrogel polymer and (vi) drying and finishing the water-absorbing polymer, wherein blowing agents having a particle size of 100 &mgr; m to 900 &mgr; m are added to the aqueous monomer solution prior to the addition of the initiator and the start of the free-radical polymerization.