Does smoking cause blighted ovum?

Doubt it. Blighted ovum (or anembryonic pregnancy) is more related to a chromosomal or post-conception error. Nothing you can do to prevent or cause these. Smoking however, can increase infertility, miscarriage, growth restriction, and preterm delivery. No to mention the neonatal health problems including sids...So, if you're planning a family; quit, eat healthy, exercise, & update your exam.
Probably not. A blighted ovum occurs when an egg is fertilized and placental tissue develops (causing a positive pregnancy test) but no baby forms. While it is possible that environmental exposures to toxins (such as nicotine, tars, carbon monooxide, etc) could affect the early pregnancy in such a way, there are no definitive studies that would document this relationship.