baby measuring big at 20 weeks scan, please help.

[raymum]

hi, this is my second pregnancy, i had 20 weeks scan and the report says all is ok but the baby is on 97th percentile,

HC, AC and FL all above 90th percentile. sonographer booked me for growth scan in 2 weeks.. what does it mean? i cant stop worrying about this, i am only 5.3 small frame . my 1st was average 7.1 pounds. does anyone know how do they calculate percentile, does the calculation depend on mothers size? anyone had similar experience if yes what happened in growth scan?

[ella'smommy]

My 2nd is also measuring big, but my husband is very tall, so I'm attributing it to his genes (I'm also 5'4). I'm 32 weeks now and the baby has measured 2 weeks ahead my entire pregnancy, until today actually measuring 4 weeks ahead in the 86th%. Is anyone in yours or the father's family tall? My DH is over 6'5 so once my gestational diabetes test came back normal I've attributed this big baby to his genes (my OB has never expressed any concern). I actually haven't gained any weight in the past 6 weeks even though I clearly feel and look bigger, I'm assuming because the baby is consuming everything I eat and more, lol!

I think the % is based on what is considered a typical range across the population. Have you had a chance to talk to your Dr/midwife to see what they are looking for with the growth scan?
 

[phathui5]

Growth measurement via ultrasound is notoriously unreliable. Don't let them stress you out.

[katelove]

The percentile are based on the measurements of lots of babies ( don't ask me when or where the data was collected!). It doesnt have anything to do with parent's size. The ultrasound machine's software them plots your baby's measurements on a graph based on that data so you can see where your baby fits within the averages. If your babe is on the 90th percentile line that means that 90% of babies measure smaller at that age and 10% measure bigger. Your babe is still within the range of normal for gestational age, s/he is just at the higher end of the normal range.

I wouldn't be too concerned. It is very unusual for a healthy, well-nourished woman to grow a baby she can't give birth to. And the weight estimate is +/-15% so bear that in mind too.

[erinmattsmom88]

I wouldn't worry about what the ultrasound says re: size... especially at 20 weeks. Not reliable at all. I know this from experience. I had to be followed by a perinatologist towards the end of my first pregnancy. I had several ultrasounds the last 2 months. At 5 weeks left in the pregnancy, they told me my DD was measuring around an 8 lb baby. They freaked out and told me to slow down my eating??? They were very "worried" I'd have a very large baby. They, along with my regular OB, talked me into an induction at 38 weeks for macrosomia. I bought it and went ahead with it. And, of course, the induction failed (daughter wasn't ready) and I had a c-section for failed induction. I knew better, but they scared me into it. Anyway, daughter was 8 lbs, 7 oz at 38 weeks. Going by what they were telling me, I thought I had a 10-pounder or more on the way.

[dayiscoming2006]

Yep, I agree with the rest. Ultrasound is not super accurate at size determination. And my good friend is only 5 foot tall and had two bigger babies. I think they were both 8 + lbs. I think pelvis size matters more than height. It's pretty rare to carry a baby too big to pass through vaginally though. 

[raymum]

thanks ladies that was reassuring :)

[thegingirl]

I wouldn't worry about it either way. First, ultrasound measurments are not terribly realiable to begin with, so they could be way off on size. But if they are, and the baby is in the higher ranges of "normal", that doesn't have to be considered a problem.  I'm 5'2" with a small frame, my DS was born at 40 weeks at 11lbs, 5oz. The 3rd trimester ultrasounds actually measured him smaller, at between 9 and 10 lbs. They are not always accurate on the high end or the low end. And no, I didn't have gestational diabetes and was at a healthy weight per BMI considerations. I had no complications and my DS is a healthy, happy 6yo who is still off the growth charts. He's 4"4' now, and just started kindergarten in the fall. Some babies are bigger, and it doesn't mean doom and gloom for the pregnancy, the birth, or the child's life afterwards. What matters is going to be not letting yourself be pushed into a treatment plan you don't agree with based on what size they think the baby may be, and not stress yourself out worrying about whether baby is "too" big or not. Babies come in all shapes and sizes and all those shapes and sizes can result in natural, healthy pregnancies, deliveries, and lives. Be happy, mama.    

[spughy]

I agree with the above posters - ultrasounds aren't the most accurate things when it comes to baby sizes, and even if they are, having a big baby isn't really a problem - positioning and your body's alignment is MUCH more important.

I'm 5'0", my first baby was 8 lb 14 oz and delivered vaginally - with her frickin' ARM OVER HER HEAD.  Oh, and posterior until right before she came out (she flipped around in the birth canal). That was the difficult part.  It wasn't that I was small or she was big, it was that she was decidedly uncooperative.

I'm not pregnant with my second and my baby is also measuring in the 90th percentile, size-wise, at my 20 week ultrasound.  But, comparing notes from last time, he/she/it also seems much better positioned in there, or my body's stretched out in the right ways, or something.  I haven't had any of the discomforts with rib pain or pubic pain that I had at this point in my last pregnancy.  So I'm reasonably reassured that things are ok.  If I can get a semi-large baby out with all that other stuff going on, I'm sure nothing short of 12 lbs as long as things are lined up properly is going to be an issue.

One thing you can do is just work on your body alignment.  Don't tuck your pelvis, don't sit for long periods of time, don't wear ANY heels at all, stretch out your calves and hamstrings daily, and visit the "spinning babies" website to see how to do inversions to help baby get positioned properly.

And one more point - I have a friend who is barely taller than me - her first baby was OVER 12 lbs and she delivered at home, vaginally, with next to no tearing.  It was just a long, slow labour and her body was fully ready by the time he came out.  So don't let any doctors give you grief and tell you it's impossible!

[pokeyAC]

I agree with everyone else. Ultrasounds after 20 weeks are notoriously unreliable for measuring size accurately. Even Consumer Reports recommends against having them as they are unnecessary and unreliable for measuring size. It increases health care costs and interventions. If it were me, I would decline the u/s unless there was a specific health problem they are looking for.

[Sol_y_Paz]

Shorter than you with a small frame and was told one of mine was measuring quite big also in a growth scan, something like the 87% percentile.  I was not measuring big.  It was wrong.  The baby was under 7 lbs and even today tends to be on the smaller side.  The growth scans aren't always correct.  I do know someone who was measuring large and also the baby was in the scans, she had a 13 pounder but this was her 2nd 13 pounder so she had a feeling.  It can vary when it comes to measurements.