Non-invasive Chromosomal Examination of Trisomy Study

Inclusion Criteria: 1. Subject is at least 18 years old and can provide informed consent. 2. Subject is planning a hospital delivery. 3. Subject has a singleton pregnancy with a documented gestational age between 10 weeks, 0 days, and 14 weeks, 2 days, inclusive, at the time of the study blood sample collection. 4. Subject is planning to undergo combined first trimester prenatal screening that includes NT measurement, and when indicated, serum screening with total or free β-hCG and PAPP-A. Exclusion Criteria: 1. Subject has known aneuploidy. 2. Subject has active or history of malignancy requiring major surgery and/or systemic chemotherapy. 3. Subject has a twin demise at any gestational age. Twin demise includes any reductions, spontaneous or elective, after sonographic identification of a second (or more) gestational sac. Any clinical, sonographic, or other testing that suggests twin demise would serve as an exclusion criterion.