Miscarriage at 7 weeks with little c antibody titer level 1:512. Did little c cause miscarriage?

Impossible to say. Many pregnancies in women at age 35, as many as 30% to 50% can be lost due to miscarriage in the first 8-12 weeks. The question is did you ever have fetal heart tones detected on ultrasound? Many early pregnancy losses result from lethal mutations in the embryo. Often development seen by US is inconsistent with dates and heart activity is not seen. Talk w/ your OB re: their opinion of future plans.
No. The pregnancy is too early that little C caused the miscarriage. The fetal red blood cells have just developed and it is too early to illicit an immune response to cause fetal anemia and death.