If a normal heartbeat is seen on an ultrasound during this early period in pregnancy, then there is less than a five percent chance of this type of miscarriage occurring. Sadly, about one in six or seven pregnancies will be lost in the first trimester. About half of the time the loss is due to some genetic abnormality of the fetus and the remainder are unexplained. Usually these genetic abnormalities are not recurrent. Some factors known to be associated with these types of miscarriage include smoking, excessive radiation, certain drugs or infections.
Some pregnancy losses occur in the second trimester.
These are much less common. There are different types of blood work and examinations of the fetus that can assist the doctor with discovering the cause of the miscarriage. If the cause is known, then sometimes steps can be taken to prevent this from happening again. Lastly, but perhaps most important, is the emotional impact of miscarriage. Likewise, there is nothing that one can do to prevent a miscarriage that is inevitable.