The family and marriage transformation in Russia and post-soviet countries of Eastern Europe was started after the collapse of the USSR. Estonia is one of the examples of post-soviet country in which marital and fertility behavior of population was rapidly changed. At the same time, since first post-war decades Estonia accepted the Russian migrants throughout a long time. Research shows that adaptation of the Russian population in Estonia has proceeded slowly, and patterns of matrimonial behavior of the Russian migrants and their descendants in Estonia tend to be closer to base patterns of ethnical Russians observed in Russia. The ‘Generations and Gender’ Survey data were used to estimate and compare the impact of high-order unions in fertility among the Russian and Estonian population in Estonia and Russians in Russia.

Our results show that the contribution of births in high-order unions to total number of births significantly increased both among Estonians and Russian population in Russia, as well as among Russian migrants in Estonia. At the same time, the reproductive behavior of Russians in Estonia has common features with behavior of the Russian population in Russia: the share of births in cohabitation is less, and length of the time interval between the first and second births in the continuous union is bigger, than for Estonians. However, there are signs of some changes in reproductive behavior among Russians in Estonia born after 1970.