baby’s head abnormally big??

the baby is 19 weeks here in this ultrasound & i can’t stop looking at his head. the lady doing the sono didnt say anything wasnt looking right but they arent able to say anything, usually the actual doctor has to go in and tell you. But i’ve seen other’s baby’s ultrasounds at 19 weeks and their baby’s head doesnt look as large and my son’s... should i worry