Screening tests in the second trimester are usually performed between 15 and 20 weeks. They involve detecting a protein and three hormones. The presence of these hormones alone indicates Down syndrome in 69% of the cases, and detecting all four (the protein and the three hormones) indicates Down syndrome in 81% of the cases. Also, neural tube defects can be predicted in a good number of cases if the protein is detected in blood.
The tests of the first and second trimester screenings can be combined to confirm birth defects such as Down syndrome in a relatively larger number (90-95%) of the cases.
A range of tests are recommended during pregnancy to make your pregnancy safe, check and assess the development and well-being of you and your baby, as well as screen for conditions. Some tests are done at almost every check-up. A few others are done only at certain times during pregnancy, or if you have certain problems. Blood tests and urine tests are two routine tests conducted during pregnancy.
Blood tests
Blood tests are done to know your blood type (A, B, AB, or O; Rh positive or Rh negative), immunity to German measles (rubella), and haemoglobin levels. The tests also reveal if you are suffering from conditions such as hepatitis B, syphilis or AIDS.
