The UN membership did not really change the state of democracy in Sweden.

Sweden approved universal and equal suffrage for men and women 1917 and enacted it in the first election 1921. Sweden was part of the Legue of Nation pre-war and continued to be a democracy troughout ww2.

Tage Erlander was the leader of the social democratic party, which dominated Swedish politics post-war and he served as prime minister 1946 (on the death of Per Albin Hansson) until 1969 when he retired. He won no less than seven democratic elections durting this era. Leading the largest party and the government for so long meant that he had a huge influence over the country.