Are you suggesting she informed the whole world that +Joesph is not the father of the Child? Do you think she announcned that her Child is God Incarnate, conceived and born in a supernatural way?
She said no such thing because no one asked her. Everyone presumed the Child was +Joseph's and was no different than any other human child, including the way He was born, and therefore His Mother was considered "unclean" for 40 days, as any mother would be in the Jewish custom of the time (and in the Eastern Orthodox Church).
She knew the repercussions of such candidness.
"She said no such thing because no one asked her"
Let's see, Joseph knew and was going to put her away until God intervened. Elizabeth knew, and Simeon and Anna knew since they knew the prophecy and were waiting for Him. Anna told everyone about Him. But it doesn't make any difference who knew what. The Law is clear that if a woman gives birth to a male child she is impure. Lev. 12:1, "If a woman have conceived seed, and born a man child: then she shall be unclean seven days...". There is no evidence that His birth was any different than any other male child; the angelic announcements excepted.
Actually, people back then could count to nine. "Son of Mary" is, in a patriarchal culture, another way of saying "father unknown." A taint that dogged our Lord wherever the family moved.