I've just had my 2nd baby and he was bigger. 1st was 7lb 7oz, 2nd was 8lb 13oz but it is different for everyone and there can be other factors like the sex of the baby can make a difference, girls tend to be smaller than boys. I'm sure they'll monitor you closely the further along you get, if not make sure you make a point of it being a priority.
not really I'm one of 4 and the 3rd youngest and I was the smallest baby. My brother also has 2 boys and his second was smaller. My 1st was 7lb 6oz and they told me I'm expecting a 9lb baby I'm hoping not tho.