The key word in article 25 is of course adequate. "Everyone has the right to a standard of living adequate for ... "
The world could maybe support 9 billions Bangladeshi or Ethiopians. It certainly can't support 9 billion Americans, or Australians, or Swiss.
The crux is that the only real effective measure to bring down birthrates (apart from sheer violence like the Chinese did) is development. That and education, especially the education of women, how Bangladesh proves.