Are first borns lighter at birth than their younger siblings?

[Posey]

In my extensive research (well asking around friends ) it seems that most first babies are lighter than the next ones. My first was 9oz lighter than my 2nd, and dh and I, both 2nd born, were substantially heavier than our older siblings.
Is this your experience? How did your babies weights differ?
Does anyone know if this is a recognised fact or is it just the case with the people I know? Is there a reason for this?

a bit:
dd1 8lb 4.5oz
dd2 8lb 9.5oz (both about 2 weeks 'over' dates)

DS ... at 40wks + 5 days ... 10lbs 1/2 oz
DD ... at 40wks + 3 days ... 10lbs 10 oz
I daren't think about having a third

ds 3080g / 6lb 12.5oz
dd 3150g

dd was 10 days late too so not much difference at all.

dd was 7lb 5oz (13 days late)
ds was 8lb 3oz (8 days early)

me 7lb something
younger sister 8lb something < this is what my mum said!! got a good memory like me

I've heard that first borns are usually the smallest. Being 29 weeks gone with no2 and a first-born at 9'10 I'm hoping to buck the trend. But I've heard people say that there second was lighter.
eg recently a friend gave birth 1st 8'10, 2nd, 8'2.

I've noticed on this thread though that people generally seem to be having big or average or small babies. Would be very surprised if this one weighed in at more than a few ounces less than 9lb.

Both of mine weighed the same so no difference other than maybe a fraction of an ounce

Ds - 9lb12oz - 12 days late
Dd - 10lb2oz - 14 days late