Low concentration of fetal DNA mostly refers to the relatively low concentration of fetal DNA in the blood of the pregnant woman extracted during non-invasive DNA testing, which is commonly used for screening of fetal chromosomal abnormalities. This situation may be caused by specimen quality problems or the pregnant woman’s own factors. 1. Problems with specimen quality: If the blood of the pregnant woman is not properly preserved, such as long storage time or high temperature and high humidity, the structure of fetal DNA in the blood will be damaged, and then the concentration of fetal DNA may be low. 2. Pregnant women’s own factors: Pregnant women’s gestational weeks are small, fetal DNA has not yet entered the bloodstream, and the DNA concentration in the blood itself is small, which may be the reason for the low DNA concentration in the extracted blood. It is recommended that pregnant women go to the hospital for non-invasive fetal DNA test between 16 and 22 weeks of pregnancy to ensure the health of the fetus. When the concentration of fetal DNA is low, it is recommended to take blood test again, and if necessary, amniocentesis can be performed as prescribed by the doctor. Consultation with a specialized doctor is recommended for specific cases.