Editing Miscarriage (section)

===Amniocentesis and chorionic villus sampling===
[[Amniocentesis]] and [[chorionic villus sampling]] (CVS) are procedures conducted to assess the fetus. A sample of amniotic fluid is obtained by the insertion of a needle through the abdomen and into the uterus. Chorionic villus sampling is a similar procedure with a sample of tissue removed rather than fluid. These procedures are not associated with pregnancy loss during the second trimester but they are associated with miscarriages and birth defects in the first trimester.<ref name="Alfirevic"/> Miscarriage caused by invasive prenatal diagnosis (chorionic villus sampling (CVS) and amniocentesis) is rare (about 1%).<ref name="Agarwal-Alfirevic-2012"/>