Not everybody knows. I'm almost as pregnant as Beyonce and just my family and a few close friends know. For a couple who were previously so protective of their private lives it does seem odd they've gone for broke with publicity for the pregnancy.
No offense, but are people following you with cameras daily, watching your every move? If Beyonce didn't announce it like she did, it would've been all over magazines and blogs that she was pregnant, so she got to announce it first.