36+2 and really confused by presentation scan measurments - any idea?!

[shouldIbecrossaboutthis]

I had a presentation scan today as I'm having a Home Birth and just wanted to see if the baby was head down as the MW wasn't sure at last check up. Had to pay for it, £60 or so, it was really really nice to see the baby and the thought of the scan has kept me going over the past 3 weeks.

The only weird thing is the measurements. The Head Circumference is 40+2, the Belly Circumference is 40+2 and the Femur Length is 40+2. The babies weight (which I think they generally get wrong anyway) is 7lb 11oz.

So does this mean the baby might come early, or that the baby is going to massive, or that he's just had a growth spurt & needs a bit more baking and will be the same sort of measurements in 4 weeks time, or something else?

PS. The height of my uterus was 34cms @ 35+3 weeks .

I'm fearing for my vagina if I'm honest!

impatient bump. Even though I know everyone is going to say he will be here when he is ready

Anyone??!

Sounds like you're cooking a whopper! Best person to advise would be your midwife. How reliable are these measurements anyway?

Musomathsci thanks for answering. Hopefully they aren't very accurate but I'm not sure really. They said the femur length is very reliable, but they're maybe biased!?

I'm seeing the midwide on Friday but I'm too nosey & impatient to wait till then.

What kind of units are those "40+2" in? Is it an actual unit of length (i.e. centimeters, millimeters, inches), or is it relating the baby's dimensions to some sort of average weight baby?

I had loads of growth scans with DS (with the NHS), and all his measurements were written down in millimeters, with measurements also plotted on little charts showing where the measurements sat in relation to the average for that gestation.

I'm guessing the "40+2" can't be millimeters, as a typical baby would have a bigger head circumference and abdominal circumference than that by 11 weeks (and would weigh nowhere near 7lb in that case), but otherwise I'm clueless.

Thanks StormGlass, I've just looked at the measurements again, the aren't all 40+1 I just got carried away in my "my fanjo is going to break!!!" state

The measurements were

Head Circ: 351mm = 40weeks
Abdominal Circ: 345mm = 39w 1 day
Femur Length: 72mm = 40weeks

These numbers mean the baby is currently 7lb 11oz apparently and according to my dating scan I was 36+1 when these were done. My fundal height was 34cm at 35+3 weeks.

In my notes there are some graphs for head circumference and abdominal circumference. I'm not medically trained in anyway so have no idea if I'm reading the graph right, but I think it says @ 36 weeks the biggest measurement in the normal range (top line) is:

340mm for head circ
340mm for abdominal Circ

It's a bit confusing really because I don't get how my fundal height can be 34cm but the babies bones are 40 week old? Where is this baby hiding!?

Looking at the (really quite small) charts in DS's scan reports, it looks like the measurements you quote are around or above the 97th centile for 36 weeks.

But bear in mind that if baby's not in the best position during the scan, the sonographer can easily get the measurements a bit out. And as the measurements are fed into an equation that gives the estimated weight, slightly wrong measurements mean a wrong estimated weight.

I had a growth scan the morning I went into labour with DS - the scan estimated his weight at 3lb 9oz. He was 4lb 6oz when he was born 18 hours later, which is a big difference.

They'd obviously missed a few millimeters off somewhere when doing the scan. I'm sure that they can get it wrong in the other direction too.

No idea why the fundal height might be different though. That's probably one for the midwife!