Many women shy away from amniocentesis for fear of miscarriage—but the link between amniocentesis risks and miscarriage has been widely overblown.
The risk of amniocentesis causing a miscarriage has been wildly overblown.
“The tests, the tests came with a risk of miscarriage, and I had already had two miscarriages.”
We do not know how many pregnant women like Van Delft shy away from amniocentesis or chorionic villus sampling (CVS)—the only prenatal tests that can definitively diagnose fetal genetic disorders like Down Syndrome—out of fears of miscarriage. No one has studied this question. But the number is likely considerable.
And that’s unfortunate, because the risk of miscarriage from these tests has been wildly overblown.
Amniocentesis and CVS are the only tests that can definitively diagnose fetal genetic disorders.
Yet many women shy away from these tests because they fear a miscarriage.
Why amniocentesis might cause miscarriage
Let’s back up a second to review how amniocentesis works.
During the procedure, a needle is inserted into the uterus to pull out a small amount of amniotic fluid (amnio). A laboratory technician then analyzes the DNA in these samples.
The procedure carries a small risk of infection, which can lead to miscarriage.
You can read more about the procedure and the reasons to consider the test here.
How often does amniocentesis actually cause miscarriage?
Reputable sources like the Center for Disease Control states that the risk of amniocentesis causing miscarriage is about 1 in 200.
But these estimates are outdated.
They derive from studies conducted in the 1980–before the routine use of ultrasound during these tests, a practice widely viewed as having dramatically lowered the risk of miscarriage. In other words, the older estimates are almost surely overblown.
Studies since the 1980s find a much lower risk of miscarriage from these procedures, one too small to be accurately estimated and often not even statistically distinguishable from zero. For instance, a large prospective Danish study of over 140,000 pregnancies found no impact on miscarriage risk. And a comprehensive meta-analysis of 21 studies conducted in the 2000s found a small non-significant post-procedure bump in the chances of miscarriage: about 1 in 1000.
The chances of miscarriage after amniocentesis is small:
about 1 in 1000.
Amniocentesis risks—do they matter?
This is a personal question. For some, the answer is “No” – any additional chance of miscarriage whether 1 in 100 or 1 in 10,000, is too much to bear. That’s totally understandable.
But for me personally, and for lots of other women, an added a 1 in 100 chance of miscarriage is too high. But a 1 in 500 chance? For me, that was worth it for the additional information and peace of mind.
These tests have come a long way. With recent advances in genetic knowledge and analysis, amniocentesis and CVS can now detect a much wider spectrum of genetic disorders than they could just a few years earlier. This is a benefit relevant to all expecting parents regardless of their age.
Learn more about the benefits of diagnostic genetic tests in the second post in this series on amnio and CVS.
Or check out our Complete Guide to Prenatal Testing ebook.