Cubs at birth weigh between 450 and 850 grams, a fraction of a grown female polar bear which during pregnancy put more than 500 kilos on the scale, according to Nuremberg zoo.

Polar bear cubs are born almost naked and it takes them up to two months to be able to stand up on their feet.

According to German media, Rostock zoo will ensure Sizzel and her babies are not exposed to any type of stress for now.