Prenatal screening for birth defects is the process of performing certain tests to provide information to parents about whether their fetus has a genetic disorder that can lead to birth defects.

The first trimester (first 3 months of pregnancy) is the time to conduct prenatal screening to detect certain genetic disorders in the baby early, especially Down syndrome (trisomy 21) and trisomy 18.

Thalassemia is a hereditary hemolytic anemia caused by a deficiency in the synthesis of one or more polypeptide chains in the globin of hemoglobin. The word thalassemia is a Greek word meaning sea blood disease, because it was first discovered and is common in the Mediterranean region. Depending on the deficiency in the alpha, beta or both delta and beta chains, it is called α-Thal, β-Thal or delta –β Thal.

Prenatal tests can help a pregnant woman know if her fetus actually has a certain disorder. Prenatal screening and diagnostic tests are offered to all pregnant women.

Non-invasive prenatal testing (NIPT) uses cell-free DNA (cfDNA) in maternal blood and has very high sensitivity and specificity when screening for abnormalities such as trisomies 21, 18 and 13. In large studies, the sensitivity for trisomies 21, 18 and 13 was 99.7%, 97.9% and 99%, respectively, while the false-positive rate (FPR) was only 0.04% for each trisomy. In addition, for monosomy X (Turner syndrome), the sensitivity was only 95.8% and the false-positive rate was 0.14%. With the above parameters, NIPT is a screening test with very high accuracy. However, NIPT is still only a screening test and cannot replace a diagnostic test.