My tsh level is 17. i recently found out i am pregnant, about 5 weeks. i take synthroid (thyroxine) .125 mg. can this level cause a miscarriage?

No, don't stop!: Don't stop your synthroid! to do so could threaten your pregnancy. However, you definitely need to talk with your endocrinologist and see if you're taking it properly. If so, you probably need an increase in dose if your TSH is 17. Stick w/brand name rx and work closely with your doctor as you need for replacement can change during pregnancy.