Doctors have a new way to check a baby’s genes before birth, and it could replace much riskier testing methods currently in use.
For years, non-invasive prenatal testing (NIPT) has let doctors screen pregnancies for certain genetic problems using nothing more than a blood sample from the mother. It’s a big improvement over older methods, but it only catches a limited number of conditions. To get a full picture of a baby’s genetic health, doctors have generally had to rely on invasive procedures like amniocentesis or chorionic villus sampling (CVS), both of which involve inserting a needle to collect a sample directly from the womb, carrying some risk to the pregnancy.
Now, researchers have developed a technique called non-invasive fetal sequencing (NIFS) that promises to close that gap. Instead of checking for just a handful of conditions, NIFS scans nearly 23,000 genes (essentially the baby’s entire exome) using only a sample of the mother’s blood. It was presented at the annual conference of the European Society of Human Genetics by Dr. Christopher Whelan.
Many expectant parents choose to skip invasive testing altogether because of the risks, discomfort, cost, or simply because it’s hard to access. Yet those invasive tests remain the only way to get truly comprehensive genetic information. Dr. Whelan and his team set out to build something that offers the same level of detail without the drawbacks.
To test how well NIFS works, the researchers studied 565 pregnancies, each at around 17 weeks. They analyzed tiny fragments of fetal DNA that circulate in the mother’s bloodstream, then used advanced computational tools to spot genetic variants across the baby’s genome. They compared these results against direct genetic sequencing done after amniocentesis or CVS in the same pregnancies.
The results were striking: NIFS picked up between 95 and 99% of the genetic variants found through invasive testing, depending on the type of variant involved. More importantly, it caught 97% of the variants tied to serious, clinically significant conditions, that standard non-invasive tests would have completely missed. The study even turned up some surprises along the way, including twin pregnancies with unusual tissue and cases where a mother’s DNA had been altered by a past bone marrow transplant from a male donor, something that can throw off standard NIPT results.
Beyond accuracy, NIFS has practical advantages. It’s expected to cost much less than invasive genetic sequencing because it builds on lab technology that’s already widely used, and it skips the need for any medical procedure. It also requires only slightly more sequencing than invasive tests do, and can be used earlier in pregnancy, as early as 10 weeks, when only a small fraction of the DNA in a mother’s blood comes from the placenta. Even at those very early, low-DNA stages, the test still lined up closely with results from invasive genetic sequencing.
Looking ahead, the research team plans to keep refining NIFS so it can detect even more genetic variants, and they’re working to expand their studies with the goal of eventually offering this kind of screening to all pregnant women. Dr. Whelan believes the approach could eventually work alongside future prenatal treatments, catching conditions early enough to act on them before birth and even providing some of the information usually gathered through newborn screening, months ahead of time.
Alexandre Reymond, who chaired the conference and wasn’t involved in the study, was equally enthusiastic about the breakthrough, calling it “a tour de force” that could reshape the future of reproductive medicine.