To ask, or not to ask?

Today at work I confronted an ever-more-frequent conundrum:  is it okay to ask a woman if she's pregnant? And if so, when is it okay?

Assuming, of course, that she hasn't chosen this helpful shirt.

My general rule for this is: never.  It is NEVER okay.  I mean, that's a very personal question, and there are many good reasons a person might not want to answer.  Directly asking puts the person in the position of having to lie to you if they aren't ready to go public with the news yet, and I don't like doing that.  In fact, I recently called out a coworker for asking me if I'm pregnant.  (No, and also, WTF?  Do I LOOK pregnant?  Is it so wrong to want a milkshake at 8am?  Sheesh.)  But, maybe I'm wrong? Maybe sometimes you can ask?  Let's back up.

Like this, but larger.  Much.

My no-asking rule comes from experience.  When I was a teenager waiting tables in a diner, I had a regular customer who dressed like she was pregnant.  She was a pretty big girl, but it was her her wardrobe choices, more than her size, that led stranger after stranger to happily chirp, "when are you due?!?" at her.  To which she generally grumbled "I'm not."  Her clothes were definitely late nineties preggo style, no question, and so to an extent I wondered why she brought it on herself, since she clearly found it annoying to be constantly asked about her nonexistent baby and reminded that she could stand to lose a few pounds.  One day she actually snapped at someone who asked her, and said "I should get to wear comfortable clothes without nosy strangers asking me about the contents of my uterus!"  And, you know, she was totally right about that.  So... you can't ask someone who looks pregnant if she's pregnant; that's rude.

At that same diner, one of my fellow waitresses was pregnant.  She shared her happy news with us after 10 weeks or so, and we were all very excited for her.  I didn't have any shifts with her for a week or two, and then when I saw her again, I asked her, all smiles, for a baby update.  And she burst into tears.  She'd miscarried.  And was devastated.  So... you can't even ask someone you know is pregnant if they are pregnant, because the answer might be something they aren't really wanting to discuss with you.

And, finally I know that you should not ask someone who doesn't look pregnant if she's pregnant.  There are many unpleasant scenarios there: 1. she's probably not, and you just implied that she's fat.  2. she's trying to get pregnant, and you just reminded her of her struggles.  3. she is pregnant, but isn't ready to tell anyone and now has to lie.  4. she doesn't want to have kids and isn't pregnant, but her mother, her mother in law, and random people at work tell her all the time that she ought to be and she's sick of it and it isn't frankly your damn business.  

BUT- today I came upon a group of coworkers discussing baby names at length and in a way that did not seem hypothetical, and to my knowledge, none of them was expecting.  What to do?  I dithered, but stayed silent, except to object to the name Gunter, on general principles.  Gunter is a terrible name regardless of who might be expecting.  My friend Kali (hi, Kali!) came in, listened to the conversation for a while, and  helpfully asked the room at large "is someone pregnant?"  Erica happily confirmed that she is, indeed.  (Congrats, Erica!)  And, I felt like Kali had gotten it right.  In that situation, it seemed okay.  So, perhaps one can generally inquire of a group if that group is loudly and publicly discussing baby names?  Is that the only exception to the rule?