Religious persecution
The primary limiting factor for Jews to immigrate to the United States was simply the will and cost of immigrating. After that, the next largest impediment was the quotas set up by the US in the 1920s to bar Eastern and Central European immigration (which also included Jews among Germans, Poles, Ukrainians, Czechs, and Slovaks).
Widespread poverty was a primary factor that helped fascist leaders gain power in Eastern Europe. Russia is an example of an Eastern European country.
Negative
Jews joined the much larger wave of immigration from Eastern, Central, and Southern Europe to the United States in 1880s-1920s. Jews left Eastern Europe for many of the same reasons as Poles, Russians, Ukrainians, Hungarians, Austrians, Germans, Italians, and Spaniards left for America. There were more economic opportunities in America, American laws made immigration relatively easy, and steamship speeds and costs made long distance boat travel more accessible. In the Jewish case, an additional push factor were the numerous pogroms and Anti-Semitic attacks throughout Eastern Europe.As is typical among the European communities in general, the Jews who tended to make the voyage were more modern-leaning. As a result, the Jewish community in the United States tended to have a far lower percentage of Hasidim and Orthodox Jews than the European Jewish population and a much higher percentage of Liberal Jews or Maskilim than in Europe.
The War Brides Act (Public Law 271) was enacted in 1945 to allow spouses and adopted children of United States military personnel to enter the U.S. after World War II.[1] The law temporarily lifted the ban on Asian immigration and the quotas on European immigration that had been established by the Immigration Act of 1924. The provisions of the War Brides Act were extended and amended by the Alien Fiancées and Fiancés Act of 1946 and the Soldier Brides Acts of 1946 and 1947. The Immigration and Nationality Act of 1952 removed race as a limiting factor in immigration, and made possible the entry of military spouses and children from South Korea after the Korean War. ~ Wikipedia
The most common push factor is poor prospects in the country of origin. Contrary to a widespread misconception the very poorest usually don't have the money to migrate. Other push factors include harassment and persecution. The reasons might also be economical,geographical,political and religious
Not the only reason but yes
Decreased Birthrate
the push factor is for scandinavians.
Natality Mortality Immigration emigration If I'm not mistaken.
Being discriminated against for your religion
Being discriminated against for your religion