In 1942, the Germans own estimate for the number of Russian, Polish and Ukrainian women with child from German soldiers and officers numbered over one million. Such an extraordinary figure is plausible as the invading German army numbered almost three million.
Birth control has always been very primitive from Tsarist Russia to the end of the Soviet Union (abortion was the primary method of birth control at the end of the Soviet Union with an average of four abortions per woman over the course of her life).
Russia and the Ukraine had been often enough invaded and life was nasty, brutal and short enough that – whether for cultural reasons (historical memory) or genetic (those strongly inclined to resist the Golden Horde left no children at all) – Russian women tend to offer a warm welcome to benevolent foreigners. There was always something mysterious and attractive about the foreigner in Russia. Just as there is something alluring and mysterious about Russian women, who are certainly the most beautiful in the world.
One basis of the attraction of Russian women to foreign men is the different personal habits. Historically, alcoholism in Western European men does not reach the extent that it does in Russian men (with the shameful exception of the Finns who drink enough to be an embarassment to Russians when on binges to Petersburg). Even when alcoholic, the Western European man remains a functional alcoholic, consuming daily cocktails, wines and spirits but at a level which allows him to work a normal day and interact normally with neighbours and even with his own family.
Women don’t care much for tea-totalling men (such abstinence hints at an absence of love of life and pleasure), but alcoholics have even less appeal (inability to work or to create or maintain a suitable home, danger to herself and her children via alcholic violence, eventual sexual impotence). So a permanent liason with a foreign man offers much greater hope for a clean and long-lasting home for both her and eventual children. In romantic terms, a marriage free of alcoholism offers hope for a better couple.
Previous German settlers to Russia (especially the Volga Germans) had earned a well deserved reputation for husbandry, sobriety and fidelilty.
No doubt the opportunity to trade sex for food and favour for many offered the same appeal in Russia as it did in conquered France.
In light of the above, it is not surprising that so many Russian and Ukrainian women found themselves pregnant. As long as they entertained the notion that their invaders’ intentions were ultimately benevolent they would happily give themeselves up to fate (fatalism is endemic in Russian philosophical and even in practical ethical thought) and see what happens with their new admirers.