The mother bear's body proteins actually break down to provide glucose in order to nourish the young while they are still inside her. And since the baby bears obtain very little nutrients while still inside the mother, they are born premature. To make up for the lack of nutrients during gestation, the milk of bears is more rich in nutrients than other carnivores. Because the milk is so rich in fats and nutrients, young bear cubs do not need to drink as much milk as other carnivore cubs. In fact, polar bear milk is the richest milk in the bear family.
Cubs remain with their mothers for two and a half years.
During this time they are taught how to hunt. Polar bears acquire this disease by ingesting infected fish and seals, which commonly harbor the parasite. Humans often get roundworm from eating poorly cooked bear meat and fish, which they commonly do in the arctic. External parasites are practically nonexistent, due to the cold temperature. Unlike most other bear species, the polar bear is pretty much left alone.