Regardless of whether you have heard anyone use the term vulgar, one of the definitions of vulgar is, “lacking refinement;” another is “of ordinary people’s language” and, indeed, the term “baby bump” is vulgar by that definition. I have been around plenty of pregnant women and myself was one some 32 years ago and, no, that term was never used. I don’t know about “Texas,” or North Carolina, but, trust me, religion has nothing to do with it.
I have noticed that the past several years have shown an increasing decline in manners, specifically in regards to the use of language. There is much in our language that, while not directly profane, is very vulgar. I admit I have occasionally uttered words that years ago would have been very improper for a lady to say (e.g. the word(s) crap or crappy as in “I had a crappy day”) and remember being chastised for saying that word.
I try to stay classy and have my own struggles, so I definitely won’t be adding “baby bump” to my vocabulary.
YMMV.
I feel VERY classy as I watch my baby bumps growing bigger and bigger each day :*) and my husband and my daughter are quite proud of the babies too (after all we went through for them to be here) so I guess we will have to agree to disagree. :-)