How Genetics Affects Infertility and Miscarriage
As a genetic counselor specializing in preconception and prenatal genetics, I know that many patients have trouble trying to have a baby. In fact, it is estimated that one in eight couples will have some form of infertility. Even though it is common, many couples feel isolated as they watch friends and family bring home a gift they so long to achieve. However, it is often hard to talk about this subject even with those who are closest to us. So, couples are increasingly going online to find information and support. But how do you know if the information is accurate or good?
Fertility was once thought of as primarily a female issue. As our understanding has increased, we find that men are just as likely to play a significant role. We also are starting to understand the genetic origins of infertility and miscarriage. Here, I will explore how genetics are changing our understanding of infertility and miscarriage.
It is common to have trouble conceiving
If you and your partner have unprotected sex on a regular basis but have not yet conceived, there may be an underlying issue. In the past, most problems were thought to be either a female hormonal or anatomic problem. We are now discovering that genetics play an important role in infertility.
If a man has a low sperm count, there may be an underlying genetic reason. For example, men that have a chromosome translocation (where chromosomes swap material) have a greater chance for infertility and miscarriage.
Another example of how we are using genetics is when we find out that a woman has premature ovarian failure, or POF. POF also may have underlying genetic issues. These may include being a carrier for Fragile X syndrome or a chromosome issue.
What if the cause of infertility is unknown?
Modern testing has found that even if all preconception testing is normal, an embryo may start off with the wrong amount of genetic information at conception. This can lead to miscarriage but it is also plays a significant role in infertility.
Today, using in vitro fertilization (IVF) and preimplantation genetic screening (PGS), we are now able to test embryos for chromosome issues prior to transfer to the uterus. Studies using new array technologies have shown that, on average, 70 percent of embryos produced during an IVF cycle will have a chromosome abnormality. Studies also have shown that this is not related to IVF itself, but is a primary reason for infertility.
It is well known that the risk for chromosome issues increases with age, but chromosome issues are not just the result of age and are much more common than once believed. In fact, they are now considered to be a significant reason for infertility, miscarriage and failed IVF.
It has long been estimated that 15-20 percent of recognized pregnancies end in loss; of that number, estimates are that 20-50 percent are due to an underlying genetic issue. Because we are now able to detect pregnancy earlier, we are finding that very early miscarriages are extremely common.
In the past, when miscarriages were tested, we often did not find an underlying genetic reason. New testing options give us much more information about why miscarriages happen. A specialized type of chromosome test makes sure we are testing the right tissue and also can identify if an abnormality came from the egg or sperm. Since the onset of using this technology, we have found that about 70 percent of losses prior to 10 weeks gestation have an identifiable genetic issue.
What is the future for genetics and infertility?
Genetic counselors are a good resource for couples unable to conceive.We are only just beginning to understand the genetic basis of miscarriage and infertility. It is likely that scientists and geneticists will discover that single gene conditions like Long QT syndrome play a role in early pregnancy losses. However, we do know that a significant number of conceptions will start with a chromosome issue. For some couples, this may manifest itself through miscarriage while other couples may be unable to achieve a pregnancy.
There are new studies that have shown with the use of PGS, we can reduce the risk for miscarriage. One study found that by using PGS, they were able to reduce the risk for couples with recurrent loss from approximately 34 percent to 7 percent. Additional studies now suggest that PGS can reduce the risk for miscarriage, failed IVF and having a child with some genetic conditions.
Our understanding of the role genetics plays in fertility has changed significantly in the last few years. Unfortunately, these technologies and advances are not well understood throughout the medical community. This is why genetic counselors are a good resource for couples unable to conceive. Genetic counselors are trained to help patients understand family and health history and provide resources to aid in future decision making.
If a patient has had multiple miscarriages or has tried for a few months without success, they should also consider visiting a reproductive endocrinologist. These specialists have the expertise to see the big picture and offer a treatment option tailored to your circumstances. With proper understanding and treatment, the healthcare community is more capable then ever at helping you achieve the ultimate goal of bringing home the miracle of a baby.
Patients can find a genetic counselor in their area by using NSGC’s “Find a Genetic Counselor” tool.
Jay Flanagan, MS, CGC, is a member of the National Society of Genetic Counselors and is a preconception/prenatal genetic counselor at Sanford Health in Sioux Falls, South Dakota.