"Oh Just You Wait"

There is nothing I find less supportive than the phrase, "Oh just you wait." Pregnancy, the time in your life where you're questioning everything and confident about little, seems to be when I've heard this bogus support line the most.
Here's how most conversations go.
Seemingly interested supportive friend, family member or just nosey passerby, "Wow, you're pretty far along, how much longer do you have?"
Seems innocent right? Don't drop your guard yet, regardless of your answer, there's only one line this type of person fires back.
Me, "Three more months, I'm due in August."
Seemingly supportive person who's about to flip roles, "Oh just you wait. You're going to have to deal with the hot weather, and your feet are going to swell, and don't forget you will never be able to get comfortable."
And bam, the supportive train has just derailed and you're faced with one of those people whose only purpose is to make you feel like you could never be prepared enough for what lies ahead. There's no getting this train back on the track, you're bewildered and the ensuing conversation is generally a nod or smile while you try to figure out what just happened. If you're like me than your defenses are in overdrive and you're refuting any possibility that there could be challenges ahead. I've found myself telling people I love the heat and humidity more often than a newborn needs their diaper changed.
This conversation, in various forms, happens so frequently lately. Whoever thought, "How was your Mother's Day" would be a trap for the just you waits? I'm now on edge talking to the "just you waits" and usually prepared to give them a verbal wallop back. Sure people chock it up to the hormones, but what if you were constantly put on the spot and told, whatever you're going through right now will be so much worse in a few months. Whatever happiness you feel about your exciting new adventure, curb it, because it's not all rainbows, sunshine and butterflies.
I think it's the dubious nature of the question that bothers me so much. Here I am innocently thinking someone cares what I'm going through only to be slammed with a comment that makes me feel foolish for feeling one way or another. The comment even has a way of making the most neutral response feel as though it was very wrong to feel a certain way.
My suggestion to all those who ask someone how they are doing, or feeling, to do it genuinely. You shouldn't have a hidden agenda to launch into how things are tough for you or to let off some of your negative steam. Acknowledge their response as something that person owns and you can't possibly be the person to judge how they are feeling or will be feeling. I think the sentiment of walking a mile in their shoes fits nicely here because unless you're in my exact same predicament, coupled with all my experiences to date, you couldn't possibly know what lies ahead of me, and you couldn't possibly tell me to wait for something to get more challenging.