Anyone else gestational age not match the size baby is measuring? — The Bump
3rd Trimester

Anyone else gestational age not match the size baby is measuring?

So I’m supposedly 28 weeks, but at my 10 week sonogram, doctor said the due date may be a week sooner and then at the 20 week one I and baby were measuring a week bigger (21 weeks for baby and 29 fundal height). So we scheduled another sonogram to check growth and on Monday baby was measuring 31 weeks and is apparently 3.5 pounds already! WTH?! 3 weeks is a big difference! So to me, the due date is off but the doctors office seems stubborn about that and don’t change it... my doctor is out of town until next week and now I’m freaking out that either something is wrong with baby or I’m doomed to have a very painful delivery and/or forced to have a C section I don’t want. The nurse who called today wasn’t helpful at all and kept saying it’s a big baby and apparently is in the 90th percentile. This is my first but I have talked to friends and no one else had anything similar happen so I don’t know what to appreciated!!

Re: Anyone else gestational age not match the size baby is measuring?

  • As time goes on, US measurements become more inaccurate with a wider margin of error. Earlier scans are most accurate for due date prediction. So maybe you might have baby a week early, but at this point, nobody would change your due date. Later scans can be off by a pound or two, even, so only time will tell when your baby will arrive. Don’t freak out. Women deliver all sizes of babies vaginally every day. You have 10-11+ weeks to go and see how baby grows. 

    FWIW, my due date got moved to a week later based on an early US (I knew ovulated late), and I went into labor exactly on her original EDD. She also was smaller than what her 36 week scan predicted. Babies do what they want. 
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  • meggymemeggyme member
    As others have said, late US’s are pretty inaccurate. At 37 weeks my baby was measuring around 7lbs and she was born 2.5 weeks later at 7lbs 1.5oz. I feel like sometimes doctors use US’s to confirm their expectations even though the level of uncertainty doesn’t necessarily confirm that (I had GD which often means big babies, and the US confirmed a baby on the larger side, which she wasn’t).

    That said, unless you’re going for an elective CS (which it doesn’t seem you are) there’s not much you can do about it. Focus on what you can control, prepare your body and mind for labor, practice some pain coping techniques, have a few last minute date nights and evenings out with friends, try and make life easy on yourself after baby arrives by making freezer meals and stocking up on essentials. Having a newborn is no cake walk whether you went med free or had a CS.
    DD1: June '16 DD2: March ‘19 :::: Married since 2011 :::: USN Wife ::::
  • Thank you for easing my mind!
  • I did pass the glucose test, so that shouldn’t be the cause of a larger baby but the nurse yesterday did say that my doctor may want me to do the 3 hour one anyways 😐 I just mostly hate waiting for answers.... 😩 but thank you both for the reassuring answers! 
  • So my baby consistently measured ahead on US, as did my bump, and I too passed my glucose test. At 32 weeks he was already estimated at 6 pounds by US. Baby boy came a few days early and was over 11 pounds. I delivered him vaginally without any medication. The size of the baby is not predictive of your delivery experience. You will likely be offered a c section if the baby is predicted over 10 pounds, but ultimately it is up to you. You can do anything you put your mind to! 
  • Everyone else is spot on. 

    It's pretty uncommon for due dates to be adjusted based on fundal height because of how much it can vary. With my second, I was measuring right on. Then, my baby flipped to breech and was sitting very high (I had an ultrasound to confirm position, and when they put the scanner down low, my uterus looked empty! They had to move it up to see her bottom), and I measured two weeks ahead. Two weeks later, the baby had flipped to head down and once again was measuring right on.

    Even if your baby is "big," that's as likely as not not a bad thing. I have now had two larger babies - my first was 8 pounds, 12.5 ounces (which is half an ounce away from an official macrosomia, or "big body," diagnosis) and my second was 8, 11. And both were born outside the hospital with no pain meds and quick deliveries. I don't say that to brag but simply to say having a "big baby" is not, in and of itself, a bad thing or a huge risk. The vast majority of women can vaginally deliver their baby, and diagnoses of cephalopelvic disproportion are often wrong. (Source:

    Also, fwiw, I found labor to be much easier with my second (smaller) baby, but the actual pushing part and delivery was worse. It really depends. I had a second-degree tear with my first and a shallow first-degree with my second. Healing was pretty quick and almost painless. I took a six-mile hike 2.5 weeks after having my first. 

    Also, do some googling on how inaccurate weight estimates based on ultrasound are. They can be off by a lot, so definitely don't take them as gospel and push back if your doctor seems to.
  • I agree! U/s aren't always accurate at determining baby's weight. Try not to stress about something that may not be an issue. I know it's gotta be frustrating though! If it makes you feel better, I know someone that gave birth to a 10 lb baby about 5 minutes after they got to the birth center😉 Don't be so quick to throw in the towel!
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