Miscarriage Risk After Amniocentesis

Different Studies Show Different Pregnancy Loss Rates After Amnio

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Different sources cite a different level of risk for miscarriage after an amniocentesis. Which one is correct?

What Is Amniocentesis?

Amniocentesis is a prenatal test. During this test, the doctor will insert a needle into your uterus through your abdomen to draw out a sample of amniotic fluid. The sample can be used to perform tests for birth defects, genetic problems, lung development and infections in your developing baby.

What the Statistics Usually Say About Miscarriage Risk After Amnio

Many women are terrified of amniocentesis because it carries a small risk of causing a miscarriage, usually within four weeks of the test. Most sources cite the risk of miscarriage after an amniocentesis to be around 0.5 to 1 percent. Although that's a low risk in most situations, a 1 in 200 chance of losing a baby because of an informational test is unacceptable for many pregnant women.

What Recent Research Says

There's some evidence, however, that the those number may not account for modern techniques and methods. A widely reported 2006 study found evidence that the real miscarriage risk after amniocentesis might only be 0.06 percent, or a 1 in 1,600 chance.

The researchers took into account that women who opted for amniocentesis might have already been more likely to miscarriage for reasons unrelated to the test - such as a higher maternal age or having had a positive screening test for abnormalities - and that miscarriages that occurred after an amniocentesis might not always be attributable to the procedure itself.

After that study, the Washington University School of Medicine analyzed its own information from 1990 to 2006 and found that the risk of miscarriage after an amniocentesis was only 0.13 percent, or a 1 in 769 chance. According to this data, 0.97 percent of women who had amnio before 24 weeks had a spontaneous late miscarriage or preterm birth, but miscarriage also occurred in 0.84 of women who did not have an amniocentesis.

The researchers concluded that the difference was not statistically significant.

A review of studies on miscarriage risk from amniocentesis and chorionic villus sampling published in 2015 concluded that the risks for both are much lower than are currently quoted.

Interpreting the Risk of Amnio

So, amniocentesis may not be as risky as many have believed. But it's hard to make any kind of sweeping generalizations about the risk because it might vary by the individual woman's situation and other factors. The skill of the practitioner performing the test does not appear to be an important miscarriage factor, but research shows it may affect the quality of the sample that's retrieved. 

The truth is, the real miscarriage risk of amniocentesis is still uncertain. If you're considering amniocentesis for any reason and you are worried about the risk, it's OK to ask your practitioner any questions that may be on your mind. A few other problems that 1 to 2 percent of women experience after amnio are cramping, spotting or leaking amniotic fluid.



Akolekar, R. Beta, J. Picciarelli, G., et al. (2015). Procedure-related risk of miscarriagefollowing amniocentesis and chorionic villus sampling: a systematic review and meta-analysis. Ultrasound in Obstetrics and Gynecology.

Diagnostic amniocentesis. UpToDate. January 5, 2016.

Amniocentesis. March of Dimes. October 2012.

Eddleman, K.A., Malone, F.D., Sullivan, L., et al. (2006). Pregnancy Loss Rates After Midtrimester Amniocentesis. Obstetrics & Gynecology.

Gioriandino, C. (2007). After midtrimester amniocentesis the risk of spontaneous pregnancy loss was 6 per 10 000. Evidence-Based Medicine.

Odibo, A.O., Gray, D.L., Dicke, J.M., et al. (2008). Revisiting the Fetal Loss Rate After Second-Trimester Genetic Amniocentesis.

Amniocentesis: What You Need to Know. Royal College of Obstetricians and Gynaecologists. 2006.

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