Preachers12,
I can give you a doctor's opinion. I am an anesthesiologist, but I studied obstetrics as all medical students are required to do, and my wife herself had a blighted ovum for our first pregnancy.
The blighted ovum means that there was no fetus forming in the egg sack. The cells that were growing in your wife only formed the placenta. These cells produce the hormone called bHCG. This is the hormone that produces a positive pregnancy test; however in your case there was no baby. The cells were producing tissue to provide nourishment for a baby, but there was no baby. I believe your wife may have had some bleeding or miscaraige at 6-8 weeks of pregnancy as is the usual course for a blighted ovum. These types of pregnancy were common before the advent of extemely sensitive testing to detect early pregnancy, they used to be interpreted as late menstrual cycles.
Religiously, I do not think that conception took place as the cells forming in your wife could never have matured into a human being. They were only forming support structures to nourish a baby that did not exist.
My wife went through anguish during her time. She would ask me, "How can there be no baby, when I have a positive pregnancy test?" No medical mumbo jumbo could console her, I only offered my support. Incidentally, the doctors told her not to get pregnant again for six months, but she wanted to be pregnant again right away, and she was pregnant within a month, we now have a perfectly healthy son, 6 and daughter 5.
Hope this explanation helps, you are in my prayers during your time of sorrow,
Jerome