Pregnancy 35 and Older Community
13.8k Members
865286 tn?1293092001

25 weeks baby measurements looks 1 week behind

Had an ultrasound yesterday. My babys measurements looked 1 week behind. AC measurement was at 4 percentile. I am 25 weeks. anyone experienced this?
5 Responses
1039620 tn?1272597604
I would try not to worry too much about the one week difference. The farther along you are the more ultrasounds can be off, sometimes up to two weeks, unlike earlier ones that are only off by a few days. As for the AC (abdominal circumference) percentage, it can be smaller if you and your husband are smaller people, which will mean that your baby may also be smaller. It's a little early now to determine, but if you look at it like this, a normal 7lb baby is the 50 percentile, and 6lb baby is 25 percentile and a 8lb baby is 75 percentile. You need to remember since you are only at 25 weeks, a LOT can change before your due date. The baby goes through many more growth spurts before then and all these numbers can change dramatically. Being only a week behind from the ultrasound is really nothing to worry about, so try and relax, I know, easier said than done. :)
480331 tn?1310407129
Both my babies measured ahead by 2wks..don't put too much merit into this,  u/s can really only "guesstimate" approximated weight/length.  Your baby will be just fine : )
377493 tn?1356505749
U/S are not accurate for dating this far along.  My little guy has been measuring ahead since end of first trimester as well.  No cause for worry at all....you might find he stays a bit behind, or suddenly has a growth spurt and shoots ahead...or back and forth.  He is normal!  
349463 tn?1333575176
I wouldn't worry at all. My baby would go a week ahead or behind several times while I was pregnant.
951946 tn?1263568983
I concur with everybody that the u/s measurements are not as spot-on as you might think. They are really estimates. In fact, 3rd trimester u/s are notorious for misjudging the size of the baby by up to TWO POUNDS in either direction!

Did they measure your uterus from the outside with a measuring tape? My midwife says that the measurements roughly correspond with 1 cm per week. So at 25 weeks, if you're between say 23cm and 27cm on that measurement, you're fine. :)
Have an Answer?
Didn't find the answer you were looking for?
Ask a question
Popular Resources
Get information and tips on how to help you choose the right place to deliver your baby.
Get the facts on how twins and multiples are formed and your chance of carrying more than one baby at a time.
Learn about the risks and benefits of circumcision.
What to expect during the first hours after delivery.
Learn about early screening and test options for your pregnancy.
Learn about testing and treatment for GBS bacterium.