Hi! Many thanks for your question on eHealth forum!
Well high BP can cause miscarriage but in later half of pregnancy usually. Also the BP is not very high to have resulted alone in miscarriage. Alternatively, yes, stress of any kind, of which miscarriage is one, can cause higher BP.
High BP can be due to kidney, heart and liver problems. It can also be hereditary as you have, called essential hypertension in which there is no other cause. You can consult your PCP and run tests to see if any cause can be detected. PCOD should also be thought of and so also thyroid problems.
If no cause can be detected, you can take a mild antihypertensive after discussing with your doctor. Hope this helps. Take care!