Not checking HCG levels?

Jenny
Hi. I'm 4 weeks 4 days along and it is my first pregnancy. I've noticed that many people on Glow have been posting their HCG levels. My OB didn't scheduled my first appointment until I'm 8 weeks along. Why does some OB docs check HCG and not others? Is it a standard to do so or a depends if it is a high risk pregnancy?