Prenatal genetic testing

pregnant dna maskMany women choose to have testing during pregnancy to learn whether their future child is likely to have a genetic condition. The most common condition tested for is Down syndrome, but there are many others. Different tests can give women different levels of certainty about what to expect from their pregnancy and birth, but no test can predict the future 100%.

There are several types of screening tests that don’t look at DNA directly, but look at other factors that may show unusual symptoms in the developing fetus. Most women have at least one ultrasound test during pregnancy, which can show clinicians whether the fetus is developing typically. Many women also have serum screening, which looks at enzymes and other substances in the mother’s blood to see if they are within normal ranges.

Prenatal cell-free DNA screening also looks at the mother’s blood, but it examines tiny pieces of DNA from the fetus and placenta that circulate in the mother’s blood while she is pregnant. It is more accurate than other screens, but only looks for a few genetic conditions–and like any screen, it is sometimes wrong and needs to be confirmed. Prenatal cfDNA screening is also sometimes called non-invasive prenatal testing (NIPT).

Finally, there’s diagnostic testing, which requires getting a sample from inside the uterus to look at the DNA of the developing fetus. One type of diagnostic test is an amniocentesis. Another is chorionic villus sampling (CVS). These tests must be done by a specialist, but they are very accurate and can find many more genetic conditions. It’s important to remember, though, that even these tests cannot predict everything about a future child, since genes can manifest in very different ways in different people, and we are still learning what many of our genes actually do.

And some women and families choose not to have any testing of the fetus at all. No woman is ever required to have prenatal screening or diagnosis. However, it’s important for every woman to have good prenatal care to safeguard her health and the safety of her future child. Any reputable prenatal health care provider can offer prenatal care, including important tests to monitor the mother’s health, without the need for testing the fetus. Regardless of what women choose about prenatal testing, they can make healthy choices for themselves and their families before, during, and after pregnancy.

 

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