Gray zone range is the value within the gray area of the test. The gray area range needs to be reviewed with attention to the current test results which show that all tests are usually negative. The Hepatitis B Pentathlon can be tested to determine if the Hepatitis B Surface Antibody is positive. It is normal if there is no hepatitis B and the hepatitis B surface antigen and syphilis antibodies are negative, as are the antigenic antibodies for HIV. Gray zone range results are not clear enough between high and low risk to consider further review. Generally speaking, Down’s syndrome screening targets a certain range of groups. It is not suitable for pregnant women of advanced age, and is prone to inaccurate testing and the need for multiple tests. The gray zone range is mainly because the situation is not very clear and another non-invasive DNA test is needed. In addition, non-invasive is not recommended for pregnant women with a history of genetic or other diseases.