From American Pregnancy Association:
What is a blighted ovum?A blighted ovum (also known as “anembryonic pregnancy”) happens when a fertilized egg attaches itself to the uterine wall, but the embryo does not develop. Cells develop to form the pregnancy sac, but not the embryo itself. A blighted ovum usually occurs within the first trimester before a woman knows she is pregnant. A high level of chromosome abnormalities usually causes a woman’s body to naturally miscarry.
Many women assume their pregnancies are on track because their hCG levels are increasing. The placenta can continue to grow and support itself without a baby for a short time, and pregnancy hormones can continue to rise, which would lead a woman to believe she is still pregnant. A diagnosis is usually not made until an ultrasound test shows either an empty womb or an empty birth sac.
What causes a blighted ovum?A blighted ovum is the cause of about 50% of first trimester miscarriages and is usually the result of chromosomal problems. A woman’s body recognizes abnormal chromosomes in a fetus and naturally does not try to continue the pregnancy because the fetus will not develop into a normal, healthy baby. This can be caused by abnormal cell division, or poor quality sperm or egg.
How can a blighted ovum be prevented?Unfortunately, in most cases a blighted ovum cannot be prevented. Some couples will seek out genetic testing if multiple early pregnancy loss occurs. A blighted ovum is often a one time occurrence, and rarely will a woman experience more than one.
The chance of this happening to K&M was probably higher than most, simply because with age comes more risk of chromosomal abnormalities. I have to believe that if this embryo truly did have a chromosomal abnormality, this might have been a blessing in disguise, knowing that they intend to terminate a pregnancy resulting in chromosomal defects. Better to miscarry now, I would think, (As if there's EVER a good time to miscarry - There's not.) than to carry the baby longer and go through the hell of making a conscious decision to terminate a baby with a beating heart. Every day you carry that baby is another day that you love it even more. Others might not agree and I understand that.
So... what are the chances of this happening to the last 4 frozen embryos? I don't know. That question echoes in my mind. They've not done genetic testing on them as their RE believes the risk of damaging one or more of the embryos is greater than the risk of an abnormality. (??) It's also costly. So, who knows?