I am with Trinaluce on the people parking too close to my car door so I can barely get out - obviously people who park next to me after I've left don't know I'm pregnant but it is still incredibly rude and inconsidereate and annoying!
I used to child mind and had 3 stage 1 car seats in the car and people would still park really close on both sides so it was almost impossible to get the 3 children (all under 2) back into the car and belted in - and that would happen in "child orientated" soft play places and woodland playground car park (where there was usually loads of room to park a bit further away) not just general town car parks.
Where we live 2 children is the norm (though there are 2 families in our tiny village with 5) and one mum I have known for ages said basically "Oh well, it can happen to anyone" when I told her I was pregnant, implying it must have been an accident, and a few people have asked directly if it was planned - but nothing nearly as rude as some on here has had!
A couple of people have asked me why I want another one when I already have "one of each" ... ?
I have had the twins comment lots of times, including from my dad (who is a doctor).
My 3 year old asks me each time I have an antenatal apt if the doctor will get the baby out this time.
My mother decided to tell me last time I saw her what a caesarian would be like, what problems I would have after, and what a caesarian baby would look like - this will be my 3rd caesarian birth (1st emergency, 2nd and 3rd planned) and though she is a doctor she has never had a caesarian herself. Also she came to stay "to help" after my last c-section and didn't lift a finger, didn't even clear her own plates away after the dinners I cooked, just wanted to sit on the sofa hold the baby "so you can get on" and to criticise my house work standards while she was about it, despite the fact I had only had the section a couple of weeks before - and was using a sling before she arrived so didn't need anyone to hold him - some understanding she showed then!
My next door neighbour offered to take my kids to Kindergarten along with hers as it must be getting a bit much for me now - very nice of her, but in the same breath she asked me to look after her 2 all afternoon after Kindergarten while she was at work as her mother had an apt - 10 minute run in the car too much for a 30 week pregnant lady, looking after an extra 5 and 3 year old alongside my own 2 for 4 hours no problem! 
Another neighbour (who has 3) spent ages telling me her 3rd (who is 6 now) was a mistake and 3 is a rubbish number!
Enough rants? Up until I was 20 weeks or so DH kept forgetting I was pregnant and suggesting non pregnancy compatible things including booking a holiday almost exactly on my due date (despite early and large bump) but he has finally got his head around it now I am 30 weeks!
Most people have been lovely though!