This study is being conducted to provide clinically annotated samples to support continued improvements in the Ariosa Test content, methodology, specimen processing and quality control.

Inclusion Criteria:

• 1. Subject is at least 18 years old and can provide informed consent;
• 2. Subject has a viable singleton or twin pregnancy;
• 3. Subject is confirmed to be at least 10 weeks, 0 days gestation at the time of the study blood draw;
• 4. Subject is planning to undergo CVS and/or amniocentesis for the purpose of genetic analysis of the fetus OR the subject has already undergone CVS and/or amniocentesis and is known to have a fetus with a chromosomal abnormality confirmed by genetic analysis.

Exclusion Criteria:

• 1. Subject has known aneuploidy;
• 2. Subject is pregnant with more than two fetuses or has had sonographic evidence of three or more gestational sacs at any time during pregnancy;
• 3. Subject has a fetal demise (including natural or elective reduction) identified prior to consent;
• 4. Subject has history of malignancy treated with chemotherapy and/or major surgery, or bone marrow transplant;

Pregnant women planning to undergo chorionic villus sampling (CVS) and/or amniocentesis for the purpose of genetic evaluation of the fetus.