It is not necessary to draw blood for chromosome testing on the 50th day of pregnancy. A blood test for chromosomes is usually needed until about 12 weeks of pregnancy. A blood test for chromosomes is a non-invasive genetic test that can be used to test a pregnant woman’s own chromosomes and to screen the chromosomes of the fetus. Pregnant women are usually tested for chromosomes after 12 weeks of gestation, when the fetus’s own chromosomes or copy number variations, such as microdeletions, microduplications of small DNA fragments, can reach the pregnant woman’s peripheral blood, which can be used to screen for fetal chromosomes by drawing peripheral blood from the pregnant woman to detect whether there is a risk of abnormal copy number variations. At 50 days of pregnancy, the concentration of fetal chromosomes and gene fragments in the peripheral blood of pregnant women is relatively low, and the test cannot produce accurate results, or the concentration is too low to detect fetal chromosomes or genes, so it is necessary to wait until 12 weeks before the test is performed. Pregnant women need to follow the doctor’s arrangement to carry out the appropriate pregnancy test, not blindly self-test, if there is any abnormality by the doctor’s guidance for standardized treatment.