Can a woman's stress and anxiety cause a miscarriage of a otherwise normal baby?

Not likely, but... Pregnancy can be stressful to some women, but more commonly has a calming affect on women, anxiety reducing, relaxation increasing. Also, will not likely change the development/normality of the in-utero fetus. Premature labor or adverse symptoms experienced--and certainly alcohol, many drugs--by the mother can affect the baby. Discuss with ob, join a pregnant women's group, relaxation exercises.