New research reveals something concerning: A common gene linked to chromosome errors can lead to early miscarriage, sometimes before you even know you're pregnant.
It's easy to forget just how amazing it is that our bodies are capable of creating life, especially given how many things—through no fault of our own—can go wrong during pregnancy.
New research from the University of Washington reinforces the fact that sometimes miscarriages happen with nothing to blame but genetics. According to Rajiv McCoy, Ph.D., a postdoctoral researcher at the University of Washington, a common gene variant that is associated with chromosome gains and losses during embryonic development can lead to miscarriage or the failure of IVF treatments. There are 12 pairs of chromosomes in a healthy person, but problems that arise during cell replication can cause them to distribute unevenly, leading to a condition known as aneuploidy, or an abnormal number of chromosomes in a cell.
"Early in human development, this process is particularly error-prone, affecting as many as 75 percent of embryos and often causing pregnancy loss as soon as five days after fertilization—before the mother even knows she is pregnant," McCoy said in the study.
How it happens
The common belief was that the mother's age had much to do with aneuploidy since her genes were responsible for cell replication in the early days of pregnancy, but McCoy said that didn't explain everything "so we guessed a genetic factor was also involved."
In the study, McCoy and colleagues from Stanford University examined over 46,000 embryos from 2,400 IVF patients and found that rs2305957, a commonly-found variant on chromosome 4 in the mother, was "strong associated' with aneuploidy risk. Aneuploid embryos were more likely to be found in patients who experienced IVF failure in the past, leading researchers to believe that aneuploidy may be what caused the IVF to fail.
"Surprisingly, about half of women had this genetic variant, and that rate is fairly consistent across populations," McCoy said. "If it's so damaging to reproduction, why does it appear so often? Why isn't it selected against [in evolution]?"
One of the beliefs is that the gene variant plays multiple roles—so though it might reduce fertility, it might have other benefits. One idea is that for ancient humans, a lower chance of successful pregnancy per sexual encounter encouraged long-term bonding between the male and female, which increased paternal investment in each child, thus improving the child's safety and health.
Can you be tested for this variant?
Of course in a time of birth control, many of us have had plenty of time to bond with our significant other before trying for a baby, and in a perfect world, you'd be able to tested for this gene variant to reduce the risk for early miscarriage. Unfortunately, McCoy says testing specifically for this issue is not currently available, but there is something you can do to check your risk. "It is a common variant that is included on many standard genotype microarrays," he tells Fit Pregnancy. "So it is part of existing [genetic testing] services, like 23andMe."
But, he adds that it's important not to panic over your own fertility based on this research. "For natural conception, this could translate into longer average time to pregnancy for women who carry the risk variant, but this has not yet been demonstrated. If such an association is established, this could be useful information for family planning."