Edward syndrome is due to trisomy 18 and the risk in repeat pregnancy is only 1-2%. The syndrome produces a recognisable constellation of both minor and major congenital abnormalities. But you need to undergo level 11 ultrasound scanning and maybe, amniocentesis to confirm that it is normal. Rubella is an infection and the two are different conditions. If you have already taken vaccination against rubella, chances are almost nil. You will need to consult a genetist, as well as an obstetrician before planning next pregnancy.