Sir, My wife was pregnant at the time of first scaning baby's heart beat OK and 5 weeks growth and they suggested next scaning between 11 weeks and 15 weeks. But 10th week we saw a blood spot and we consulted the doctor and again scaned that result says no heartbeat and only 6 weeks growth. Tell me sir what happened and chances of abortion. My blood group is o posotive and wife's is be negative

Not abortion, but a miscarriage, if the fetus is indeed no longer living.

There are 1000's of reasons and many women have them, you can test and try to determine of there is some medical issue, that can be discovered.