What are the causes of recurrent miscarriage?
Recurrent miscarriage is one of the most frustrating problems that I see in my practice. The chance of a miscarriage in women less than age 30 is about 10%, but it goes up to about one in three or up to even 50% when you're above age 40. So why is this happening?
Well, typically it’s due to the egg quality. As a woman ages, the quality for your eggs in addition to the quantity diminish. For years, we always thought it was the woman contributing to losses, but more recent evidence is actually showing that advanced paternal age if the male partner is above 40 to 45 years old, he can be contributing to miscarriage as well. In addition, other issues like infertility, autism, and schizophrenia all increase as a man gets older.
What do we look for when it comes to the causes of recurrent miscarriage? For all the possible reasons, 50% of the time, we just don’t know what the cause is. The other 50% is broken down into approximately these four areas: genetic, anatomic, autoimmune and hormonal.
With genetic causes, we’re looking at the chromosomes which we call the carrier type of the couple that is trying to conceive; the man and the woman. Less than 5% of the time, one of them can have a carrier-situation of their chromosomes. Meaning that they’re not completely lined up, there's something a little bit, where one chromosome may have stolen a little bit of information from the other. The total amount is normal, but they’re not aligned ideally. So, when it divides up to become eggs and sperm, the offspring can have an unbalanced picture and that could increase the risk of loss.
The inside of the uterus can develop as a septate uterus which is the most common abnormality with miscarriage. Septate is where the sides of the uterus normally come together and they fuse and doesn't completely core out. So, the top part of the uterus is remaining inside the uterine cavity and that septum increases the risk of loss up to about 44%. Fortunately, the incision of that septum is done surgically as an outpatient procedure through a hysteroscopy.
Polyps and fibroid scarring inside the uterus can also be a factor. And we look at those with either a little office telescope or water ultrasound to make sure the inside of the uterus is normal.
3. Autoimmune or Antiphospholipid Antibodies
There are proteins circulating in the blood of women in up to about 10% or so of women who experience recurrent loss that can actually increase the risk of clotting in the pregnancy tissue. Those can be detected with three simple tests:
- Anticardiolipin antibody
- Anti-beta2 glycoprotein
- Lupus anticoagulant (has nothing to do with lupus.)
Thyroid and prolactin abnormalities can increase the risk of loss as well as uncontrolled diabetes. One other thing that we do is we look with an endometrial biopsy and remove some cells from the lining of the uterus because chronic inflammation can increase the risk of loss.
When should testing be done?
An individual pregnancy loss affects about 10% to 15% of women; two or more losses affects about 5% of the population; three or more losses affects 1% of the population. The American Society for Reproductive Medicine (ASRM) recommends evaluating a patient or at least discussing the issue after two losses and certainly testing with three or more losses. But often, particularly for women above age 35, we'll do a complete evaluation with two or more losses. If a woman is wanting that evaluation to be done sooner, two or more losses is a reasonable point to start doing an evaluation.
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