Cases of recurrent miscarriage (pregnancy loss) are not that rare - this is a serious problem. As it has been already shown there are several causes of pregnancy loss due to infection agents.
The most usual cause of miscarriage is so-called chromosome abnormality. In most cases it is the egg that gives such a problem because the bigger number of inappropriate chromosomes comes particularly from the egg. Statistical study shows that only half of the eggs woman produces in her life time are capable of leading to a successful pregnancy. These numbers are pretty sad.
Some of these chromosomally abnormal eggs do not divide while others lose conception due to infection agents. And almost all of these eggs are not even identified as pregnancy. Possible risk of miscarriage due to chromosomally abnormal gametes (both eggs and sperm) is connected with age. The older the person is the higher the risk is. On the internet you can even find special tables that show the dependency of risk and your age (two kinds of tables are available - for men and women).
Another serious factor that can lead to miscarriage is the use of Diethylstilbestrol (DES).It has been clearly shown that DES infection agents decreases fertility and increases the risk of pregnancy loss.
All the above said causes relate to a first trimester pregnancy loss. As for the second trimester pregnancy loss different infection agents can be the case. Many doctors suppose that infection agents are the cause of pregnancy loss but this question is still open. To discover more about this reason of miscarriage special studies on infection agents are being performed these days.
These studies mainly aim at mycoplasma hominis and ureaplasma urealyticum. These infection agents are believed to be primarily responsible for pregnancy loss. Chlamydia is another organism that is also believed to cause miscarriage in many cases. But still there is a strong shortage of data in this sector and only further studies of infection agents can make the situation here clearer. As more is learned about mycoplasma hominis and ureaplasma urealyticum more answers will be forthcoming.
There is also another thing that may cause pregnancy loss. About 10% of couples that experienced pregnancy loss have different sorts of immune problems. In most cases the problem seems to be "lupus anticoagulant" - the problem with clotting. Many methods to treat this problem are in development today. For example, Cortisol and related drugs have been used. But the tests show that such treatment has no significant result on clotting and at the same time possible side effects of cortisol can be dangerous for woman's health. So, probably the best and safest treatment of clotting problem for today is using of smaller dosage of aspirin (and in some cases low dosage of heparin).
In fact, there are many things that couples can do to lower the risk of miscarriage (pregnancy loss). It is necessary to avoid all the potentially dangerous factors. Smoking and alcohol abuse can seriously increase the risk of pregnancy loss. Dietary problems can also be involved in affecting this risk. Try to lower the fat consumption and regulate your daily diet. Certain medications can also increase the risk so talk with your doctor about that.