Why are the obs so strict with my blood sugar when I am pregnant and the internists not so if not?

Babies. The results of uncontrolled blood sugars in pregnancy are high blood sugars crossing the placenta and causing "large" babies and other problems. Large babies used to seeing high sugars in utero tend to crash after birth when the levels suddently plummet. You probably worked hard at getting pregnant so why not take the best care of yourself to help your baby afterwards?
OB Complications. Diabetes in pregnancy is a very difficult problem for mother and fetus. The higher the blood sugar during pregnancy, the greater the complicatons to the fetus including macrosomia(big babies) and if significantly uncontroled death to the fetus.