Dear Gisela, I do not know whether it would be fully impossible to reunite mother and child, even if Masha would be pregnant. I do not know whether you have ever followed the story of Lily and Hope (the black bears of Minnesota Bear Research Centre), but they too got separated twice when the cub was only 4 to 5 months old (OK, not by human intervention, but nevertheless they lost each other and they were living in the wild). The second time, the separation took about one month but when they found each other again, Lily was also pregnant (during that period, she met a male and mated), however, she re-started nursing Hope. And during the following winter, Hope was still with her in the den when she gave birth to Faith and Jason and she nursed all three (!!!!) without any problem. But of course, here the situation might be entirely different and I assume that Four Paws is knowing perfectly well what they are doing. Let us cross our fingers for Masha and her little daughter Nastia.