Miscarriages Are Common
Approximately 20% of all clinically recognized pregnancies end in miscarriage, the loss of a pregnancy in the womb before 20 weeks of gestation. This percentage is higher if you include those who do not yet know they are pregnant.
I am never surprised when I hear that a miscarriage is an aspect of a patient’s history. What surprises me is that it is a topic that remains largely undiscussed, even among one’s friends and family. When I ask a patient if any of their relatives have had a miscarriage, I am often told that they are “unsure” or that, “They haven’t mentioned it” or “I didn’t ask.”
Admittedly, I have a skewed perspective as a result of my job. I imagine most people don’t make such inquires for several social reasons. Yet, while I am not saying we should encourage this habit as a general rule, I do wonder about the harm being done to patients who do not have a network or support system should they find themselves among the many who have lost a pregnancy.
Potential Causes of Miscarriages
I find there is often embarrassment, guilt, and/or shame when a patient discusses their history of miscarriage(s). And while there are various causes of miscarriage, including maternal infection, maternal conditions, hormonal imbalance, structural uterine abnormalities, and genetic factors, rarely, if ever, is a patient intentionally the cause of the loss.
Miscarrying can cause a patient to feel as if they have no control. Thankfully, they can work towards obtaining it by gaining knowledge and then advocating for appropriate care.
For example, it is important for patients to know that many potential causes of miscarriage can be clinically evaluated through bloodwork and imaging with treatment and reproductive options dependent on the underlying etiology. These evaluations are typically initiated after a second unexplained loss. Subsequent medical management options can range from more straightforward tactics, such as a prescription for antibiotics, supplemental hormones, or surgery to more involved management. Genetic factors often require the latter.
Genetics and Miscarriages
Fifty percent of all first trimester miscarriages are due to a chromosome abnormality. Most of these are sporadic rather than inherited; in other words, they happen by chance. The most common causes include when an embryo has a missing X chromosome or an extra chromosome 16 or chromosome 22.
In approximately 4% of couples who have had two or more unexplained pregnancy losses, a balanced chromosome rearrangement (BCR) is identified in one of the partners. The easiest way I have found to think about this is by considering a well-loved book series, be it Harry Potter, Throne of Glass, or Game of Thrones.
Someone who carries a BCR typically does not know as they tend to be healthy and have no ill effects of their translocation. Their bodies have all the genetic information required to work properly. However, someone who is a carrier of a BCR has an increased risk to have a child with extra or missing genetic material that can result in a miscarriage or a live born infant with an unbalanced chromosome condition that could result in intellectual or physical disabilities.
Returning to the potential for subsequent medical management, a BCR cannot be corrected, but the risk to have a live born infant with an unbalanced form can be significantly reduced through alternative reproductive options including the use of in vitro fertilization (IVF) with preimplantation genetic testing for structural rearrangements (PGT-SR), the use of an egg or sperm donor, prenatal diagnosis, or adoption.
Points to Remember
If you have had a miscarriage, you are not alone.
If you need time to grieve, take it. If you need to talk, reach out. When you meet another person who has had a miscarriage, and you most likely will, offer them what you can from your own experience, even if it is as simple as admitting you have been in a similar situation.
If you have had two or more unexplained miscarriages, follow up with your reproductive healthcare provider to advocate for testing to investigate potential causes for this history.
This includes meeting with a genetic counselor for an in depth discussion of your history, the testing process, and result interpretation and discussion.
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