Detective Not Needed

As my First Post mentioned, pregnancy and babies are all around me.  At the moment I have three pregnant friends and several friends who I anticipate becoming pregnant any day now.  Any moment really.  Of these friends, all are married and all are trying (I define trying as not using any form of birth control).  Meaning, while I'm no Columbo, the likely outcome of those equations is impending pregnancy.

I see all of my soon-to-be-pregnant friends on a regular basis.  It's going to be a glaring change when the table orders two bottles of red and my usual wine buddy passes.  Or when my friend, who follows a fierce diet and exercise regime, has been lax about the gym and looks uncharacteristically bloated.  Or when my typically less endowed friend is busting out of her v-neck shirt.  What I'm asking is whether I'm supposed to ignore blatant evidence that my friend is with child because she hasn't confirmed the news.

Despite my lack of personal experience, I know enough to know that many women keep their pregnancy under wraps for the first trimester.  Yet, there is a large possibility (I'd wager a probability) that I will hangout with my friends during this secret first trimester, whenever it comes.  If the telltale signs of pregnancy are THERE, what do I do?  My instinct is to let it be.  A secret so big should be revealed as chosen and asking the obvious question will either ruin the planned reveal or force a really bad and transparent lie.  On the other hand, what if my friend is trying to wait until the second trimester, but desperately looking for an excuse and a person to tell.  Plus, if I don't ask and it's that obvious it will probably get awkward and force a lie anyway.

I'm in unchartered territory.

Suggestions, please.  Would you ask your friend if she's pregnant or wait for her to tell you?  Pregnant women and those formerly pregnant, what do/did you prefer?