trillian is right, some women do have big babies and then have a small bub

My first DS was born very healthy 7lb 15oz (3.6kg's) my second DS was just born on 18th Dec 2010 and was 2.2kg's so it is very possible to have a smaller bub after a big one
I dont mean to scare you by that either

Some midwifes do know what they are talking about, my midwife with DS2 felt his little bum and said he feels like he has a really small "compact" bottom lol and sure enough his bottom is tiny as and he did come out only quite small, and my baby bump was very big either compared to DS1

I say exactly the same as everyone else if you are worried i would have a scan just to make sure

Is your fundal height measuring properly??? at 28wks my fundal height with DS2 starting measuring a week behind and when it come time to have a scan at 34wks to check where my placenta was they picked up that my baby was measuring 1-2weeks behind and eastimated to only be 2.5kgs, they then organised another scan the week after and same thing he still measured a week behind and still only esitmated to weigh 2.5kgs, in the end i got pre-eclampsia so couldnt go full-term he did as mentioned above only weigh 2.2kgs, me having such a small baby though was my placenta had started to shut down and wasnt feeding him 100%

sorry for rambling on