I'm tired of people feeling like it's okay to speculate on why others aren't drinking, or pressure people into having a drink.
No, I'm not pregnant, and even if I was, you are not a detective working in the pregnancy unit because you spotted that someone held the vodka in their cranberry and vodka. No one is impressed woth your deductive skills, you are not the first person to ever joke that someone who isn't drinking is pregnant so feel free to stop patting yourself on the back. Sometimes, I just don't want a drink and that doesn't mean you have free reign to discuss the contents of my uterus. Just because I refused wine doesn't make you not a rude asshole. How about the next time you say no to fibre, I start speculating on what may be in your colon? Doesn't feel so good, does it (and with that I'm referring to both the discussion of your colon and your colon itself).
The pregnancy thing is annoying, but a bigger issue is that perfectly normal people have problems with alcohol, but our attitude towards alcohol creates a situation where those people are either forced to admit their problem, or move to a new social group. Not everyone wants you to know that they have an addiction. Alcoholism still has a stigma attached to it, and people that suffer from it should feel free to abstain from alcohol without having to declare to everyone that they are alcoholics.
My other big issue is drunk driving. We're all happy to chastise people who cause accidents driving drunk, but when I've been driving and abstained from alcohol, I've had to justify my choice. It's great that other people can guarantee that they will be able to safely drive after a glass of wine, but I can't unless I know there's a good window between me finishing it and heading home. Obviously, when I'm hanging out with people who feel like me drinking is up for debate, that window is going to be as short as I can possibly make it, as much as being drunk may make it easier to handle assholes.
Sometimes, I just don't feel like drinking. It's expensive (unless you have a good moonshine source), it messes up my sleep, or maybe I'd just like some water. It is also sometimes quite enjoyable. But guess what, regardless, I'm the one who gets to decide that for myself.
You want to be a good host? Offer once and when they say they don't want alcohol, just let them drink what they want. Are you afraid that drinking alone makes you an alcoholic? Convincing someone to drink just so you can drink without worrying about being an alcoholic is probably a worse problem.
In conclusion: you don't decide what goes into other people's bodies and them choosing not to consume something is in no way an invitation to speculate on their health, potential offspring or mental state. If you have a problem with that, you maybe should be speculating on your own relationship with alcohol, rather than mine.