I believe it is probably the same in other countries too, I know that I have encountered this same mentality in my town and other cities I've been to with my child. I was 20, almost 21, when I had my son, and I look young for my age (plus I'm very short). Anyway, I was stared at pretty much anywhere I went while I was pregnant and even after I had my son. I've been asked tons of times how old I am, if I'm married, or if I'm actually my sons sister... Yeah... It drives me nuts when people just assume things.
I've also had some rude comments from family members, mostly from my husbands family on his dads side.. Like once I forgot to put a few burp cloths in the diaper bag before we left the house, and when we were asked if we had one and I checked and said no, they reacted and said that we were irresponsible and needed to be better prepared. That might have been something silly to get upset over, but I really took offense to it, I was extremely tired and just simply forgot to put them in there.
People here generally will not judge if you have finished college, have a career, get married, own a car, and buy a house before having kids.. If you are younger than 25 and haven't done all of these things, assumptions will be made and you will get talked about.. Which is very sad because there are lots of women who are in their late teens or early twenties that are amazing mothers to their child or children. Age really has nothing to do with someones parenting ability, it really depends on the individual, how they were raised, and the environment they grew up in.
Now with all that being said, my son will be 4 this year in May and I will be 25 in July. I have learned to ignore most of the comments and all the looks I get in public, and let all the "parenting advice" from family members and the comments that offend me a bit to just go in one ear and out of the other. But it is irritating to have to hear all of that kind of stuff, and it does hurt but eventually it will get better.