There are different prenatal tests for detecting fetal aneuploidy, which are generally divided into two main groups: noninvasive and invasive. Noninvasive prenatal testing poses no risk to the fetus and mother, as it only requires a sample of the mother's blood. It can be done from the 10th week of pregnancy and is much more reliable than the combined screening test, which has a higher error rate. Invasive tests are chorionic villus sampling and amniocentesis. Regarding the detection of aneuploidy, they are only done to confirm suspicion of aneuploidy detected by noninvasive prenatal testing, as they carry a risk of miscarriage between 1% and 2%.