Hello Anitha, Thanks for writing and I do understand your concern regarding your baby. I would say you do no have to worry about the difference of 1 week between your two scan reports. Let me explain you why. Ultrasound reports determines the age of your baby using different dimensions of fetal parts. Medically they are called as crown rump length, gestational sac diameter, biparietal diameter, femur length etc. The dimensions of each are used during different periods of your baby growth to estimate the gestational age. These calculations are never 100% accurate. There is a variability interval (variations) of at least 1 week that needs to be adjusted. Hence, most of the time the difference that you have observed yourself is because of this variation. Sometimes, operator error can also be a cause but with modern technology this is rare nowadays. If you had taken your first scan in one center and the next in other this could also have caused a bias in your result. So, do not worry! Unless the ultrasound report suggested any growth related abnormalities.