Baby measuring big at 20 week scan, not fundal height. Experiences please :)

Hi Ladies,

At my 20 week scan our little boy was measuring above average, 10 days larger in all of his measurements, limbs, tummy etc (dates are correct) and at my most recent Ob appointment the Ob briefly mentioned a possible scan to check bubs size. I've heard alot of posts regarding size estimations being incorrect but was wondering if this was based on fundal height or actual baby measurements. Just looking for some experiences from ladies whose bub measured big, were they born a bigger baby? I had a natural birth with my DD and am wanting the same for this bub but a little bit of concern has crept in about his size. My hubby was a 10 pounder, could this have an affect on bubs size? My DD was a 7lb 6 bub.

Thanks :)

I'd say he would have just had a bit of a growth spurt recently :) Babies all grow at slightly different rates, so he may have had a spurt recently and will then plateau for a few weeks. I would so not trust that my baby would be big based on a scan so early in the piece (or ever, really). DD measured smack bang in her dates the whole way through, and was born 8lb9oz...which I've been told is on the bigger side, obviously to me it's just normal sized lol.

it's the ultrasounds that tend to be inaccurate and the later in pregnancy you are, the less accurate they are. 10 days isn't that much of a difference, really.
Personally, I'd avoid late scans purely for sizing, unless there's some other indicator of a problem.

Our first measured at least a week ahead in our 20 week scan. She came in at 8lbs(which I think is nice given I come from a family that usually has 9lb bundles). We had another scan at 34 or 36 (cant remember exactly) weeks and I think at that time her measurements were closer to what they "should" have been. May not have been a necessary scan, but was nice to see bubs at 34 weeks though.I got the feeling my OB ordered that scan for all his patients regardless.

both my DD's were "big" for dates. with DD1 i had insulin dependent GD so that contributed to her growth. my scan at 36wks with her predicted her to be around 8pds. she was born at 39 weeks weighing 7pd 14ounces. DD2 was big for dates from day dot measuring 2weeks ahead always. a scan at 36 weeks predicted her to be 8pd 5 ounces and she was born at 38+1 weighing in at 9pd 4ounces.

I know many ppl say the scans are inaccurate, but in my case they were pretty close....well DD2 was a bit bigger than the prediction. Her head was big at 37.5cm :o

I was told that at the 20 week scan that they dont usually get concerned unless the baby measures more than i think she said 2 weeks either way. My DS was a week behind in measurements, so was measuring only 18 weeks when i was 19 weeks at my morph scan which id say was before a growth spurt as he soon caught up and was a very healthy 8lbs at birth.

I'd say he recently had a growth spurt :)

FWIW, my sister was told her DD was 9lbs at 37 weeks, she went into spontaneous labour at 38 weeks and her DD was 7lbs 13oz.

my u/s guy said they don't care if its measuring bigger, just if its a few weeks smaller than it should be. There's a long way to go and things usually even themselves out

At 32 weeks my DD was measured at already 3 kg and I was told she'd be over 4 at birth, given that babies average weight gains around 250g a week in the last trimester. She was born at 39+5 at 3.8kg.

DS no indication he was big, no late scan, fundal height measuring spot on, he was born at 41 at 4.84kg.

Am now battling hospital policy and will probably be recommended a scan based on the size of DS :rolleyes: which I intend to politely refuse.

DD3 was measuring ahead by 11 days at the 20 weeks scan (had a dating scan at 6w3d then she was ahead at the 12 weeks scan by 4 days then 11 days I think at the morph scan.) I didn't have GD and my midwife wasn't concerend in the least. DD3 was born after a spontaneous labour at 37+4, 8lb 6oz, my biggest by far but also my longest pregnancy, dd1 was 6lb 3oz at 36+2 and DD2 was 6lb 14oz at 35+6. DD2 and DD3 were on the higher end of the percentile for their size for gestation but I had straightforward vaginal births for all of them. Im glad my body knew they were ready to come as they could have been rather large if I got to 40+ weeks ;)

Ultrasound scans can be innacurate for estimating birth size but can be useful for checking consistent growth, and as PZ said they can have growth spurts!

I was told by the sonographer who did my ultrasounds and midwives that read all my ultrasounds that my bubs was huge. I had gestational diabetes but my fundal height was perfect all the way to 41 weeks and I only put on 4.5kg for the whole pregnancy. I questioned the sonographer and he admitted there is a massive percentage of leeway they have so the scans aren't gospel. That gave me the ****s as I was worrying about birthing my third baby naturally again but scared of his size.....
Anyway at 36 week ultrasound baby was already measuring 3.7kg and roughly was measuring 40 weeks...so I made it to 41weeks and birthed him naturally drug free with no tears but constantly worrying he was going to be too big and it was gonna hurt...his weight at birth was 3.77kg which meant the ultrasound was way off... I saw the sonographer again as ds needed an ultrasound after birth and told him. He said he appreciated the feedback and thinks more research needs to be done into how the results are interpreted according to how babies are growing.
Long story short I wouldn't be worried about size. Your body will birth a baby that's right for you..

My scans with all mine put them at above average for size because of their long limbs (my husband is a giant).

With DD1 though, I had a scan the day before she was born, they put her head circ at around 40cm - and her belly the same size. And said she would be around 10 pound 4.

She was born the next day at 8 pound 11. Oh, and her head was 35cm. So I don't really trust the scans that much LOL

Scans with Miss I the whole way through put her as way ahead of dates. The scan I had at 32 or 33 weeks indicated from hc and limb length that she was going to be a very large baby. She was born at 40+5 weighing 3.5kgs and 50cm long - smack on average. Scans with Miss A put her as being a little on the small side. She was born at 41+1 at a smidge under 4kgs.

SIL was induced at 38 weeks because scans indicated her baby was small and the OB was concerned about the placenta's effectiveness. He was born at 4.2kgs

I wouldn't put too much faith in them TBH, certainly not from my experience.

My scans were all pretty much perfect for size. My ob has an ultrasound machine in his room and measures bub's head, tummy and thigh and the ultrasound machine estimates gestation and weight. With each bub my last scan before birth was no more than a week before, and the estimated weight was always pretty close to birth weight.

Thanks for your responses ladies, you have definitely eased my worries :)