Can the gestational age vary in an ultrasound?

Hello,

Welcome to icliniq.com.

I understand your concerns.

I understand why this seems confusing, but there are a few possible explanations for the difference in gestational age seen in the ultrasounds. They are as follows:

Incorrect first scan measurement (underestimated gestation at five weeks).

Early pregnancy ultrasounds (especially before six weeks) can sometimes underestimate the gestational age due to difficulty in measuring the tiny embryo.

If the first scan was slightly off, the second scan at 10 weeks may be more accurate.

There was a misinterpretation of weeks in the first scan. Sometimes, reports state "five weeks" when referring to embryonic development rather than total gestational age (which includes two weeks before conception). If she was seven weeks on the first scan, she would now be 10 weeks, which aligns perfectly.

Babies do not usually “grow faster” in pregnancy, but small measurement variations can happen due to the angle of the scan, fetal position, or ultrasound equipment. It can be a human or technical error. If two different sonographers performed the scans, they might have used slightly different measurement techniques. Early pregnancy scans have a margin of error of more or less five days, which can affect the reported age.

If concerned, ask the doctor to review both scans and confirm the most accurate gestational age. The most accurate dating scan is done between eight to 12 weeks, so the second scan is likely more reliable. As long as everything looks healthy, this difference is not a major concern. I hope you find this information helpful.

Thank you.