DEAR MAYO CLINIC: I am 32 and have had one healthy pregnancy and baby. But over the past 18 months, I have had two miscarriages, both in the first 12 weeks of pregnancy. My doctor does not recommend testing until after a third miscarriage. What do you recommend? What kind of tests can be done to determine if there is a problem?
ANSWER: Going through a miscarriage can be sad and stressful. Dealing with it more than once is particularly difficult. It is understandable that you want answers about why the miscarriages happened. Unfortunately, it is often hard to find a specific cause. There are several tests, however, that may be able to rule out certain problems that could lead to a miscarriage.
In general, a miscarriage is defined as the loss of a pregnancy before 20 weeks gestation. Because it is not a topic that receives much attention, miscarriage tends to be more common than people might think. Doctors estimate that about 10 to 15 percent of all recognized pregnancies end in miscarriage. About one percent of women have more than one miscarriage.
Your doctor’s recommendation to wait for testing until after a third miscarriage fits with traditional guidelines. However, as the risk for another pregnancy loss after two miscarriages is similar to the risk after three miscarriages, some physicians will do testing after two.
Many tests can be done to try to find the reason for miscarriages. One of the most common is called parental karyotyping. For this test, a blood sample is taken from both parents and tested for problems within the chromosomes. If any chromosomes are abnormal, that could mean a genetic disorder may be to blame for the miscarriages.
A blood test also may be used to screen for a condition known as antiphospholipid syndrome. This disease happens when a person’s immune system mistakenly attacks some of the normal proteins in the blood. It is known to cause pregnancy complications, including miscarriage and stillbirth.
An exam called a hysterosalpingogram can be useful, too. It involves injecting contrast dye through the cervix and then using X-ray to examine the uterus and fallopian tubes for any problems that may be leading to a miscarriage. Tests to check for thyroid disease and diabetes are often performed as well. Those diseases may cause complications that could result in a miscarriage. Additional tests also may be helpful depending on your age, medical background and family history.
Even if all this testing is done, the exact cause of miscarriages still cannot be determined for about 50 to 75 percent of couples. On a brighter note, though, many couples who have more than one miscarriage do go on to have a successful pregnancy. Studies suggest that number to be about 60 percent.
The fact that you already have had one healthy pregnancy raises your chances even higher. Research shows that a previous successful pregnancy is one of the most important predictors of being able to carry another baby to term. Of couples in your situation, 70 to 75 percent have another successful pregnancy.
Have a conversation with your doctor about your concerns regarding your miscarriages. If you feel strongly that you would like testing done before you attempt to get pregnant again, talk about that. Under the circumstances, it is a reasonable request.
Keep in mind, too, that in almost all cases, miscarriages are not a result of anything a mother has done or failed to do. So if you decide to become pregnant again, unless an underlying medical condition is identified that needs special care, you should not need to do anything differently. Seek regular prenatal care, avoid known miscarriage risk factors — such as smoking and drinking alcohol — and focus on taking good care of yourself and your baby. — Carl Rose, M.D., Obstetrics and Gynecology, Mayo Clinic, Rochester, Minn.