What led to Polands dramatic population decrease after world war 2?

Poland's dramatic population decrease after World War II was primarily due to the immense loss of life during the war, which included both military casualties and the Holocaust, resulting in the deaths of millions of Polish citizens, particularly among the Jewish community. Furthermore, post-war border changes and the displacement of people caused significant demographic shifts, as many Poles were forced to leave their homes or migrated to other countries. The trauma and devastation of the war also led to a decline in birth rates in the immediate aftermath, contributing to the overall population decrease.