Im not fully sure of my last period date as my cycles are irregular. Gynac said they will check baby's size in the scan. Does that actually tell how far along i am? Just curious how it works.
My mother-in-law was so confused how the doctor knew the exact week just by scanning! But yes, the baby's measurements in the early scans give the most accurate pregnancy age.
The first trimester scan measurements (CRL) are the most accurate for finding the baby's age. Later scans are less accurate for dating because babies grow at different rates.
Because of my irregular periods, we couldn't rely on my last period date. The early ultrasound size was what the doctor used to find the actual gestational age.
