Do genetics really play no part in size at early stages?

[ag123]

My first dc was 5kg/11lbs at birth and at 3yo is still massive in comparison to his peers.
Am currently pg with dc2...had 2 early private scans (I'm a terrible worry wort) at 7 and 10 weeks and just had my official scan yesterday at 13 weeks. Each one has put my edd back by 2 days. This has surprised me as I thought I was having long cycles if around 32 days (I know when you actually ovulate can vary).
This has meant that my edd has moved from the beginning of Sept to the end of August and was really hoping to hold out til Sept for the whole school-year issue (I think I am going to be strongly advised to have an elcs after all the complications last time so will probably be given a date)
Anyway, obviously the safe delivery of my baby will be the most important factor but was wondering whether I could use the argument that it may just be masuring big already so the dating measurements may not be completely accurate as a reason to delay my set date until September?

I think it does play a part, but I think it comes from the mothers side.

I was 8lb at birth, my brother 9lb.

My children were 9lb and 8lb 2oz

Due in July, different partner, so we will see!

I thought babies grow at a particular rate up to 12w gestation; their growth is then influenced by maternal factors (your size, girth, diet), then after birth their own genetic/or natural growth pattern.

I don't know if that's true. I was dated at my 8 week scan (put back a week) then put forward a week at my 12 week scan.

I dont think they will change the date from whatever you measure at 12w. No matter what you say to convince them.
Crazily both ivf babies have had the dates changed edd brought forward 2-4days.
Dc1 was born before the edd so about 4 days early.
Both dc though measured small at the early scan so made up like 6 days each between 7 and 12w

Are you being tested for GD?
As an 11lb baby and then this one measuring ahead.
Are you and dh both tall?

I think the cS are often done at like 39w, so would think that would bring you even further into august?
Dc2 was measuring just under 59th centile at 20w scan so after moving edd earlier its now showing dc is smaller for gestational age than they are, more like 60th centile and 19+3w. I think, that the early measurements, when dcs are so small(before 12w) are likely quite inaccurate. Also my dc likely have a large head and the smaller they are the more of them is made up of head.

You're probably right Naty1 I've got a feeling they will want to do cs 1/2 weeks early... Incidentally, is this only standard practice to eliminate the risk of spontaneous labour?
I'm thinking I may have more information after my fun week of 3xappts during week 16 (consultant, anaesthetist, birth trauma clinic)
And yes, have a feeling I may be being tested early for GD this time, though I never had a trace of sugar in my wee the whole of 1st pregnancy. My husband and I are both 5'10" and quite 'stockily' built.

Another 11lber!! My now 19mo was 11lbs at birth and I am currently 9 weeks with the next one! Really worrying that this one will be big too.

Dc1 - 7lb 3oz
Dc2 - 11lbs

Let's hope they don't carry on getting bigger

You don't always get glucose in urine with GD (and often you get it without GD) so definitely worth getting tested.

But that aside, two days difference is well within the margin of error. In my area they didn't change the due date from LMP unless scan was +/- 5 days.

Was your first dc a spontaneous delivery? Was it late? This would be an argument for having a history of inaccurate dating scans. (Unless my logic is failing me)

Ok, that's interesting Tarka and no Guyropes was a failed induction after probable prolonged rupture of membranes but I get what you're saying.

I was 6lb born. But 5 weeks early.
My ds was 15 days late and 11lb7oz! (I had a section after days of induction doing nothing.)
Was tested for, but apparently didn't have GD.
I also wonder what future babies will weigh, and i do not want to give birth naturally to them if they're going to be big!

And I'm only 5ft5, DH about 5ft10. So not tall either.

We're you tested properly for gestational diabetes (I.e not just glucose in urine, but proper glucose tolerance testing?)

What was your measurement of CRL? I had a scan at 13 weeks and measured 7.1mm CRL but she put my due date as the same as my LMP even though my cycles are short so I should be 3 days further along. I looked at the length 7.1 at it seems more likely the feotus is 13 weeks more than 12 weeks 5.
I think if the length is roughly what they expect they just go by the lmp regardless

Skiptonlass I definitely had to down a load of lucozade at some point but I seem to remember it being a lot earlier than the 28 weeks which is standard practice with my new hospital (though I suspect i'll have to take it earlier). And I thought I remembered that only if your results were suspect from that that you had to go and do a full gtt. At the stage that I took it I specifically remember that I passed early as I remember them making a comment about it. Could it have just developed late on?

Apparently the genes that govern individual size aren't triggered until later on in pregnancy, they really are remarkably similar up to a certain stage. Thats why dating is so accurate up to however many weeks. I talked to a dr about it when I had no known lmp date and had to rely on scans.
Although she did also say that people get far too hung up on counting days and exact EDD(am I 12+1 or 12+3, tell me!) and they generally only work on weeks.

Yeah, that's what they told me too. I was just wondering whether it could make a difference in 'extreme' cases!