i don't think your choices necessarily have to be a secret, but rather information on a "need to know" basis. just be more discerning about who you share information with and what information you just have to share.
i mean, you can tell by how flaming topics get just on this site, how passionate people are about their views on childbirth and parenting and how bold and utterly obnoxious many of them are letting others know their ways aren't right.
the last thing you need while pregnant is feeling that everywhere you turn, you have to defend yourself and/or educate people. personally, i wouldn't put myself in that position to begin with. 9 months goes by quickly. make sure your memories are fond and not frustrating.
good luck and congrats!