Prenatal testing is performed during a pregnancy to assess the health status of a fetus. Prenatal diagnostic tests are offered when there is an increased risk of having a child with a genetic condition due to maternal age, family history, ethnicity, or suggestive multiple marker screen or fetal ultrasound examination. Routine prenatal diagnostic test procedures are amniocentesis and chorionic villus sampling (CVS). More specialized procedures include placental biopsy, periumbilical blood sampling (PUBS), and fetoscopy with fetal skin biopsy.