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no risk of pregnancy loss. Diagnostic tests such as CVS and


amniocentesis provide a defi nitive answer to questions about your baby’s health. However, the more accurate information comes at the expense of an invasive procedure that carries a small risk to the pregnancy, including damage to the fetus and miscarriage.


Cell-Free DNA Testing Cell-free DNA testing may be changing the traditional options, offering more informa- tion than was available through traditional screening tests, without the risks associated with traditional invasive diagnostic tests. Using DNA from the pregnancy that circulates through your blood, a simple maternal blood test may be able to tell you about your baby’s chromosomes without any risk to the fetus. This would give you information about Down syndrome, as well as other fetal chromosomal abnormalities such as Trisomy 13 and 18. Many cell-free DNA tests can reveal


your baby’s gender before it’s even visible on an ultrasound, which may be important if there is a concern about a sex-linked genetic abnormality. One option allows for screen- ing of your baby’s blood type and potentially avoiding a RhoGAM injection if you are Rh negative. There has not been much research examining the role of cell-free DNA testing in single-gene disorders (such as cystic fi brosis), but this may be possible in the near future. While it may seem that cell-free DNA is


the answer for prenatal testing for those par- ents who want as much information as soon as possible, there are some things to consider. Most experts recommend this testing only with pregnancies at higher risk for problems, such as those in women of advanced age, at risk for babies with genetic problems, or who have abnormal ultrasound fi ndings. One to eight percent of all test results


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may have a failed analysis result, indicating that not enough fetal DNA was seen, and the test is unable to give information. Often, the blood draw is repeated slightly later in pregnancy, with an analysis sometimes possible. Most important, while early results are re-


assuring, cell-free DNA testing is still consid- ered a screening and not a diagnostic test. This means that experts advise that patients with an abnormal test result for a chromosomal abnormality undergo a traditional invasive test to confi rm it. Additionally, there is the rare possibility that the test may miss an abnormal- ity. Therefore, if you want to know about your baby’s chromosomes with complete certainty, for now the best route for you to take still may be CVS or amniocentesis. Logistically, there are several companies


that use the new technology, and they are all slightly different in the information they are able to report to you. Most healthcare providers have a company or two with whom they have set up this type of cell-free DNA testing. The blood draw occurs at the end of your fi rst trimester — at approximately nine to ten weeks into your pregnancy — and it takes about one to two weeks to analyze it and report back to you. Women expecting twins are still eligible for this testing but only through a smaller group of companies. Lastly, some insurance companies pay for


a portion of this test, and some may not cover it at all, depending upon your policy. You may have a co-pay of several hundred dollars, espe- cially if your pregnancy is considered low-risk. Given the many factors that may infl uence your decision to have any prenatal genetic testing, it’s best to talk to your provider.


Mimi Wachendorf Fradinho, MD, is an ob/gyn with Harvard Vanguard Medical Associates, practicing at Beth Israel Deaconess Medical Center, Boston.


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