Bears don't 'carry' cubs.
They breed in the spring, but the embryo basically goes dormant for the summer. The small babys crawl out of the womb in the winter while the mother is hibernating. Suckle the winter, until she wakes up, by then they are little pups. They will stay with her the entire first year and den with her that winter. The cubs will stay with her most of the next year also. Then she will run them off.
You see a sow with li'l pups, those are 1st year cubs born that past winter. You see a sow with a couple of black labs, those are second year cubs.
That is just one big fat bear.