Expert's Perspective

Early Pregnancy Loss

Early pregnancy loss, or miscarriage, is often a physically and emotionally difficult time. Many questions arise: “Why did this happen to me?” “What should I do now?” “Will I ever be able to have a healthy pregnancy and baby?" Here, we try to answer these questions.

Why did this happen to me?

Before we start discussing the reasons that a pregnancy loss happened, it's important to discuss the reasons that the pregnancy loss did not happen. The pregnancy loss did not happen because you were stressed, had a deadline at work or got into an argument with someone. It did not happen because you were ambivalent about the pregnancy, lifted something heavy, drank one or two cups of coffee or had sex. Simply put, you did not miscarry the pregnancy.

Miscarriage itself is actually very common; it is by far the most common complication of pregnancy. About 20% of all pregnancies end in a miscarriage, though if you do an early pregnancy test, that number is much higher. One to two percent of all women attempting to conceive will have 3 or more losses.

What causes a miscarriage?

When we think about causes of a miscarriage, there are essentially two categories: chromosomal causes and everything else (Figure 1). By far, the most common cause of pregnancy loss is chromosomal; when the embryo has the wrong number of chromosomes. Chromosomes are the structures that contain our genetic information. There are 23 chromosomes. We normally receive two sets of these 23 chromosomes - one set of 23 chromosomes from the egg from our mother and one set of 23 chromosomes from the sperm from our father. Sometimes, when the egg or sperm or early embryo is being formed, a mistake happens and the embryo ends up with more or fewer chromosomes than is normal. This is called "aneuploidy" (An example of this is Down’s syndrome where there is an extra copy of chromosome 21.).

Miscarriage Chart

At least 60% of first and second miscarriages are due to the embryo having the wrong number of chromosomes, and this number is probably far higher if you include very early pregnancy losses. In these cases, the miscarriage is actually the result of the mother’s body correctly recognizing that this pregnancy will not result in a healthy baby and stopping the pregnancy.

While the most common cause of miscarriage is due to the embryo having the wrong number of chromosomes, many other factors can result in a miscarriage. For a pregnancy to successfully carry to term, a lot of steps have to go right; problems in any of those steps could result in a miscarriage. For example, the embryo has to implant in the uterus and not in the fallopian tubes; the uterus must have a normal structure and not have large polyps or fibroids or certain structural abnormalities; the lining of the uterus must be free of infection; hormone levels (such as thyroid hormones) have to be normal and certain blood clotting problems in the mother would need to be treated. The goal in treating women with recurrent miscarriage is to try to identify and correct issues like these that can result in a miscarriage.

Common Causes of Miscarriage

How to manage a miscarriage?

When a miscarriage happens, the pregnancy may either pass on its own or it may remain inside the uterus. If it remains inside the uterus, your doctor may give you the option of either waiting for it to pass on its own, taking a medication to help it pass, or having a procedure performed to remove the pregnancy. The decision about which approach to take is based on a combination of patient preference and the clinical situation. The primary concern is to keep the mother safe. While heavy bleeding is normal, it is important to make sure it is not excessive.

I am often asked which of the three methods (waiting, medication or a procedure) do I prefer? The reality is that there isn't one answer that is ideal; each option has its own advantages and disadvantages based on the clinical situation and patient preference and these must be carefully discussed with the patient. In cases where it is not necessary to obtain tissue for genetic testing or where the patient strongly prefers to avoid surgery, expectant or medical management may be the best option. In cases where it is vital to test the products of conception for aneuploidy, surgery is usually recommended. While surgery provides the best chance of obtaining fetal tissue that can be subsequently tested for aneuploidy, the procedure to remove the pregnancy can cause scarring in the uterus. Scarring occurs in about 20-30% of women after three procedures and is a problem because it can make it difficult to get pregnant and/or cause subsequent miscarriages. To minimize the risk of scarring, we have recently begun using a small camera to guide removal of pregnancy tissue while minimizing injury to surrounding tissue.

Traditionally, testing to determine if the fetus was aneuploid was not done on pregnancy tissue until after the third miscarriage. The reason being that it is so likely that a first or second miscarriage was due to aneuploidy, that testing the pregnancy tissue to confirm that it was aneuploid would not be cost effective. The traditional thinking was that if a third loss occurred, genetic testing of the miscarriage tissue should be performed at that point because if it was not aneuploid, that would prompt the doctor to look for other causes of miscarriage, like the ones I outlined earlier.

I disagree with this position. In my experience, and confirmed in larger studies, miscarriage is often associated with a tremendous sense of self-blame and guilt; women (and their partners) will often blame themselves for the loss and will carry this emotional pain with them. Testing for aneuploidy after a first or second loss is important because in cases where the tissue was aneuploid, it provides a sense of closure to the woman and reassurance that the loss was not her fault. Conversely, when the genetic testing shows no abnormality, it allows evaluation for other causes of miscarriage - and treatment - to be started sooner and, hopefully, prevent the next pregnancy from ending in a miscarriage.

Testing is very accurate and reulsts are usually back within 1-3 weeks, depending on the method of testing and the lab that does the testing. Testing is often covered by insurance, but one should check beforehand, as the tests themselves are currently quite expensive ($1000-$3000, though price-reduction programs are available). One challenge is that when the results come back showing a normal female fetus, it is sometimes necessary to do a follow-up test to confirm that the cells tested were from the fetus and not maternal cells that were present in the sample.

What to do after?

After the pregnancy has passed, the pregnancy hormone levels (HCG) should be followed until they are negative. The pregnancy tissue can also be tested to see if it was chromosomally “normal” or contained fewer or more than 23 chromosomes. If 23 chromosomes are present, your physician will likely begin an evaluation to make sure other causes of miscarriage, such as uterine factors, thyroid or diabetes-related problems, or blood clotting disorders are not present. Currently physician guidelines recommend this testing commence after a second miscarriage.

Will I ever be able to have a healthy pregnancy and baby?

The emotional pain of a miscarriage is often compounded by the fear that a healthy pregnancy may not be possible. The good news is that after a few losses, the chances that the next pregnancy will be successful are good. At PEARL, we see the most challenging cases for which traditional testing has not found a cause for the losses, and a majority of our patients ultimately have a healthy, full term pregnancy and baby.

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