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What’s in YOUR blood? A simple blood test may change the face of prenatal care

SM egg2I love my kids. Really, I do. But I'm afraid that I may come across as a bit of a curmudgeon to my friends, family and even my regular readers when I write about the day-to-day life as a parent of three busy kids. Take this excerpt from my most recent contribution to our current issue of Stanford Medicine:

Most woman who have been pregnant are familiar with how the growing fetus takes over the mother’s body — slowly, at first, and then with increasing ferocity as bladder and lungs and belly are stretched and pounded. The process is quite humbling.

So when I learned that up to 10 percent of free-floating genetic material in a mother’s blood actually comes from the fetus, I rolled my eyes and snorted. First my body, and then my blood? Does the indignity never end?

Ok, maybe I *am* a bit of a sourpuss sometimes. Because it turns out that this genetic material allows us to learn some amazing things about that person-to-be. It's now possible to deduce the entire genome of a fetus from a pregnant woman's blood sample, for example. And although we're nowhere near offering that service routinely (and there's a robust conversation to be had around the use of such information in a healthy pregnancy), we can use a similar approach to screen for some common genetic anomalies with no risk to the fetus. As I describe in the article, the new, noninvasive blood test:

... can identify about 99 percent of Down syndrome cases as early as 10 weeks of pregnancy. False-positive rates reported by the companies hover at around 0.1 percent for detecting Down syndrome, and false negatives for the condition appear to be even more rare.

The article was fascinating to research and to write, and it illustrates some of the challenges of integrating new technological advances with routine prenatal care. Who should be offered the test? How shall women be counseled about the results? What diseases can we (or should we) detect? One thing is clear. Things have changed since my pregnancies. And regardless of my apparently verbal, or literary, stick-shaking, I'm truly glad that my children will have access to these advances in prenatal care when they start families of their own. You know. A long, LONG time from now.

Previously: From womb to world: Stanford Medicine Magazine explores new work on having a baby, Whole-genome fetal sequencing recognized as one of the year's "10 Breakthrough Technologies" and New techniques to diagnose disease in a fetus
Illustration by Christopher Silas Neal

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