Why did the proportion of ethnic Latvians decline during the Soviet period?

During the Soviet period, the proportion of ethnic Latvians in the population declined significantly—dropping from approximately three-fourths to little more than one-half—due to a combination of demographic loss and state-sponsored social engineering.12

The primary factors contributing to this shift included:

• Mass Deportations and Flight: Following the Soviet occupation, tens of thousands of Latvians were deported to prison camps in Siberia and other parts of the U.S.S.R., particularly during the "year of terror" and the 1949 agricultural collectivization campaign. Additionally, approximately 100,000 Latvians fled the country to Sweden and Germany to escape the advancing Red Army.12
• Large-Scale Immigration: Throughout the postwar period, the Soviet regime encouraged massive immigration of non-Latvians, primarily from Russia and other Soviet republics, to man industrial projects and military installations.132
• Demographic Trends: The decline was further exacerbated by a low birth rate that failed to ensure population replacement, a trend that persisted even after the country regained its independence.34