Miscarriage is the most common adverse outcome of a pregnancy. A miscarriage can occur
in any pregnancy and in multiple pregnancies. Doctors call this recurrent pregnancy loss or
recurrent miscarriage. What are the causes for recurrent miscarriage? What are the
standard tests done for couples with recurrent miscarriages? Stay tuned and I will explain
There are two categories of intrauterine pregnancy losses. Some pregnancies miscarry after a positive
pregnancy test but before the pregnancy can be seen on ultrasound. These very early pregnancy
losses are known as biochemical pregnancies or pregnancies of unknown location. Because they are
lost so early, there has been very little study of these types of losses. In fact, when you look at
studies of recurrent miscarriages, the researchers usually exclude couples with biochemical losses.
This is unfortunate. It means that we know very little about the causes for biochemical losses.
The causes may be similar to later miscarriages or it may not. We just don’t know.
This is important for you to understand. If you are a couple that has had three biochemical
losses, your doctor may ask you to do testing that is actually intended for people with later losses.
They may recommend treatments that are designed for later losses.
We have no evidence that these treatments are helpful for very early biochemical losses.
For the rest of this episode, I am going to discuss what doctors refer to as
clinical miscarriages. These are miscarriage that occur after a pregnancy is seen in the uterus on
ultrasound. If a pregnancy is seen outside of the uterus, this is defined as an ectopic pregnancy.
Ectopic pregnancies are not considered to be miscarriages. Ultrasound findings in clinical
miscarriages include 1) an empty gestational sac where no fetus is visible, 2) a fetus is seen but
never had any heart motion and 3) a fetus which had heart motion but then was lost afterward.
Because miscarriages are so common, doctors will usually not recommend
any special testing unless a couple has had two or more miscarriages.
Most miscarriages are due to abnormalities from the embryo. A normal, healthy embryo
should have 46 chromosomes, 23 from each parent. In the majority of miscarriages,
60-70%, the fetus has too many or too few chromosomes. These are called aneuploidies.
It is therefore important to do a chromosome analysis on the pregnancy tissue from every loss.
If a couple has had a miscarriage that is due to an aneuploidy,
no further testing is necessary. You have identified the cause for the miscarriage.
If there wasn’t a chromosome abnormality, then further testing is reasonable.
In 4-5% of couples with recurrent miscarriage, one of the parents
may have an abnormality in the structure of their chromsomes. These are called translocations. These
abnormalities can cause imbalances in parts of a chromosome and can therefore also result
in recurrent miscarriage. These can usually be identified by doing blood testing on each parent
Another cause for recurrent miscarriages are problems with the maternal immune system.
This may account for about 15% of coupes with recurrent miscarriage.
This problem is also diagnosed with blood testing and includes anti-cardiolipin antibodies,
glycoprotein antibodies, lupus anticoagulant and anti-thyroid antibodies.
An abnormal result should be repeated after several weeks to rule sporadic results.
Other blood tests that are commonly done look for several problems which can increase the
risks for blood clots in the tiny blood vessels of the uterus. Some of the tests
are for genetic mutations and some look for imbalances in the compounds
that normally keep the balance between bleeding and clotting
Another group of blood tests look for systemic diseases like
uncontrolled diabetes, and celiac disease
Beyond blood testing, it is important to evaluate the uterus for abnormalities in the shape of the
uterus, the presence of growths, masses or scar tissue, and the presence of inflammation
Our InfertilityTV bottom line is this: If you have lost more than one pregnancy,
learn what types of losses you had. If you have had recurrent clinical miscarriages,
then you should see a reproductive endocrinologist to complete testing to
see if there are any treatable factors which can reduce the future risk for miscarriage