Q: My sister just miscarried due to a blighted ovum. What is this? Is it hereditary?
A: A blighted ovum occurs when a fertilized egg attaches to the uterine wall, but the embryo does not develop. So even though the body's baby-making machinery is in place--an egg has been fertilized, a gestational sac and placenta are forming, and symptoms of pregnancy may be occurring--the embryo itself stops growing. Experts aren't sure why, but they suspect that chromosomal abnormalities may be the primary cause. The occurrence of a blighted ovum is not rare; in fact, it's suspected to be the cause of a significant number of very early miscarriages, many of which happen before a woman even knows she's pregnant. It's also not hereditary and it cannot be prevented. In fact, in most instances, a blighted ovum is unique to that pregnancy. As such, your sister is likely to have a successful pregnancy in the future.