Baby's head too small

I'm at week 33 now. I went for my mandatory ultrasound scan at week 31, I was told that my baby's head is smaller than usual. Doctor told me to come back at week 33 to redo the scan. I went back today and the ultrasound still shows that the baby head is smaller than average. The doctor adviced for me to go back in a week's time. He mentioned that baby is hiding deep under my pelvic bone that's why it's difficult to see and the size might have been under estimated. Just want to check with all the other mothers out there if you have encountered similar situation? What are some of the possible consequences for babies having a smaller head?