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The risk of miscarriage after amniocentesis is actually a topic of debate in the medical community. Some studies put it at about one in every 200 to 500 women, while others suggest the risk is actually more like one in every 1,600 women. These wildly varying risk estimates are the result of different study methodologies used to explore the risk of miscarriage after amniocentesis. Women preparing for this prenatal test should ask their physicians about specific risk factors that may make it more dangerous for them, as every pregnancy is different.
In an amniocentesis, a small sample of amniotic fluid is taken and analyzed in a lab. This test can identify certain genetic disorders or a risk of a genetic disorder. It is not possible to screen for everything and it is possible to return false positives and negatives, but the test can provide more information about a pregnancy and may be recommended for certain women.
Historically, estimates about the risk of miscarriage after amniocentesis were high, around one in every 200 tests. As the test became more widespread and doctors gained more experience, these risks declined, with individual providers having lower miscarriage rates. Additional tests controlling for more factors showed that the risk was even lower.
When a woman miscarries after an amniocentesis, it may not necessarily be because of the test. Some women are at an increased risk for miscarriage because of factors relating to their pregnancy, like age or fetal genetic conditions. Because these women were more likely to be told to have amniocentesis tests, it is possible that early estimates about miscarriage after amniocentesis were in fact artificially high because they failed to adequately account for other possible causes of the miscarriages of study subjects. A study conducted by the American College of Obstetrics and Gynecology in 2007 demonstrated that the miscarriage risk was one in 1,600, significantly lower than previously believed.
Women considering an amniocentesis who are concerned about the risk of miscarriage after amniocentesis can ask if there are special circumstances in their pregnancies that might increase miscarriage risk. They may also want to ask their obstetricians about their level of experience with this test. Ultimately, the decision to have or forgo this test is a personal one. For some women, even a low risk may be too high for them to feel comfortable. There is no requirement that people absolutely must receive this prenatal test and there may be alternatives available.