No worse than ultrasound
The term of pregnancy was learned to determine by a blood test
Ekaterina Rusakova, N+1
American and Danish doctors have developed a non-invasive and cheap method for determining the duration of pregnancy, the accuracy of which is comparable to ultrasound, according to an article published in Science (Ngo et al., Noninvasive blood tests for fetal development predict gestational age and preterm delivery).
It is determined by the content of extracellular RNA specific to the placenta in the blood. Also, in a pilot study, scientists were able to determine with 75 percent accuracy whether premature birth will occur.
Now the pregnancy period is most often estimated using ultrasound, which can be quite expensive, or by the time of the last menstruation, the assessment of which may be inaccurate. In addition, these methods do not allow predicting premature birth. It would not hurt to learn how to predict them, since about 15 million children around the world are born prematurely, and in the USA this is the most common cause of death of newborns.
Therefore, American and Danish doctors under the leadership of Stephen Quake from Stanford University have proposed a new non–invasive and cheap method - a blood test for the content of extracellular RNAs of the placenta. With its help, it is possible to determine not only the term of pregnancy, but also to predict premature birth with a sufficiently high accuracy.
Extracellular DNA and RNA enter the bloodstream as a result of necrosis or programmed cell death of various tissues. Therefore, analyzing their composition, it is possible to determine the condition of a particular organ. Extracellular DNA was used to diagnose the rejection reaction of the transplanted organ, to determine the sequence of the fetal genome, as a biomarker for the diagnosis of cancerous tumors and to evaluate the effectiveness of cancer treatment. Extracellular RNA, unlike DNA, allows you to determine not only the sequence of the genome, but also to track the expression of genes, and, consequently, the state of the organ in dynamics. Therefore, researchers are trying to adapt extracellular RNA as a biomarker to identify certain types of cancer.
In their previous work, the authors showed that by changing the concentration of extracellular RNA in the blood, it is possible to track long-term changes in the state of the mother and fetus. In the new work, the authors have developed a method for determining the gestation period by the concentration of extracellular RNAs. For the pilot study, they invited 31 pregnant Danish women who donated blood every week, and scientists tracked the dynamics. All the women gave birth on time, and the scientists used blood samples from 21 of these women to build a statistical model, and 10 to check the results. As a result, scientists were able to identify nine extracellular RNAs corresponding to genes encoding proteins specific to the placenta. By changing their concentration, scientists were able to determine the duration of pregnancy with 45 percent accuracy, which is comparable to the accuracy of ultrasound (48 percent).
Scientists also conducted a pilot study of two cohorts of women who had an increased risk of premature birth. One of them consisted of 23 people who had already had premature labor, the other 15 women had premature contractions. The study participants donated blood once, in the second or third trimester of pregnancy. As a result, 13 of them gave birth prematurely, and the remaining 25 – on time. And scientists have found that the concentration of seven extracellular RNAs from the placenta can help determine whether a woman will give birth prematurely or on time, with 75 percent accuracy.
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