It is not uncommon for there to be a discrepancy between the estimated gestational age based on your last menstrual period (LMP) and the measurement obtained from an ultrasound scan. While scans are generally accurate in determining gestational age, they can sometimes provide different results due to various factors.
One possible reason for the difference could be variations in ovulation and conception dates. The LMP method assumes a regular 28-day cycle with ovulation occurring around day
Another factor that can affect accuracy is the timing of the ultrasound itself. Early ultrasounds performed before 12 weeks are considered more accurate in determining gestational age because fetal development is relatively consistent during this period. However, as pregnancy progresses, individual growth rates may vary, leading to potential discrepancies between estimated dates.
It's also worth noting that human error can play a role in scan accuracy. Measurements taken during an ultrasound rely on the skill and experience of the sonographer performing the procedure. Small errors in measurement or interpretation can contribute to slight differences in estimated gestational age.
If you're concerned about the accuracy of your scan results, it's best to discuss them with your healthcare provider. They may recommend additional ultrasounds or other diagnostic tests to further assess fetal development and ensure everything is progressing as expected. Remember, scans are just one tool used to monitor pregnancy, and your healthcare provider will consider multiple factors when assessing your due date and overall progress.