My first had a head circumference of 35cm when he was born (early @ 38wks) and I had no tearing/no stitches. I was told 35cm was average.
This time round bub's head was 30.5cm @ my 33wk growth scan so Im expecting much the same size if not a tad bigger.

Head circumference really doesnt matter as bubs head is moldable, it squeezes and shapes to the birth canal which is why they come out with a bit of a cone-head look