During the war, played some water polo and continued swimming, winning the national 100 m backstroke titles in 1941–1943. Her brother became a water polo player around that time, and in 1943 she married another water polo player Ko Koster. After 1938, her career spiked again in 1947, when within one week of April–May she set two world records in medley relay events, and shortly after won a bronze medal at the 1947 European Aquatics Championships in the 100 m backstroke.