Prenatal testing consists of prenatal screening and diagnostic procedure, which are aspects of prenatal care that specialise in detecting problems with the pregnancy as early as possible. These could also be anatomic and physiologic problems with the health of the zygote, embryo, or fetus, either before gestation even starts (as in preimplantation genetic diagnosis) or as early in gestation as practicable. Screening can detect problems like ectoderm defects, chromosome abnormalities, and gene mutations that might cause genetic disorders and birth defects, like rachischisis , birth defect , Downs Syndrome, Tay–Sachs disease, red blood cell anemia, thalassemia, CF , dystrophy , and fragile X syndrome. Diagnostic procedure employs a spread of techniques to work out the health and condition of an unborn fetus. Without knowledge gained by diagnostic procedure, there might be an untoward outcome for the fetus or the mother or both. Congenital anomalies account for 20 to 25% of perinatal deaths. Specifically, diagnostic procedure is Prenatal screening focuses on finding problems among an outsized population with affordable and noninvasive methods. Diagnostic procedure focuses on pursuing additional detailed information once a specific problem has been found, and may sometimes be more invasive. The foremost common screening procedures are routine ultrasounds, blood tests, and vital sign measurement.