Although cases with known multiple gestations were excluded, the NATUS algorithm identified 127 (0.4%) samples as having >2 fetal haplotypes, indicative of either unreported twins, vanishing twin, or triploidy. ICD-9 codes were associated with 19.0% (5468/28,739) of women: 16.6% were low-risk, 44.1% were high-risk based only on advanced maternal age (≥35 years), and 39.3%

had high-risk codes. As expected, the incidence of aneuploidy calls was smallest in the low-risk group (0.7%), followed by advanced maternal age women (1.6%), and largest in the high-risk group (3.4%) ( Table 3). Results for the 23,271 samples without ICD-9 codes showed a similar difference in see more aneuploidy calls between women aged <35 years (1.0%, 117/11,629) and those aged ≥35 years (2.4%, 274/11,642). From 17,885 cases in the follow-up cohort, outcome information was sought for the 356 high-risk calls; 152 high-risk calls from the LEE011 mw whole cohort described above were not contained within the follow-up cohort. Information regarding invasive testing uptake was available for 251/356 (70.5%) cases that received a high-risk result: 39.0% (139) elected invasive testing and 31.5% (112) declined invasive tests, and of the remaining 105 (29.5%), 39 had a spontaneous demise or elective termination. Within the 356 high-risk calls, there were in total 58 reported spontaneous abortions,

including 16 cases categorized as TP, 2 FP, 4 with

ultrasound findings suggestive of aneuploidy, and 36 with unconfirmed outcomes. There were 57 reported elective terminations, including 30 cases categorized as TP, 5 with ultrasound findings suggestive of aneuploidy, and 22 elective terminations with unconfirmed outcomes. At the conclusion of clinical follow-up, 62.4% (222/356) of high-risk calls had karyotype information or at-birth confirmation: 184 confirmed affected pregnancies (TP) and 38 unaffected pregnancies (FP) (Table 4). Eight cases showed placental or fetal mosaicism: 5 fetal mosaics (TP) were confirmed by amniocentesis (2 inhibitors trisomy 21, 2 trisomy 18, 1 monosomy X), and 3 cases were considered FP because of confined placental mosaicism (CPM). Two CPM whatever cases were high risk for trisomy 13 and were identified as mosaics by chorionic villus sampling (CVS), one was determined to be euploid by amniocentesis, and the other did not have a follow-up amniocentesis but ultrasound at 20 weeks was read as normal. In the third CPM case, at-birth testing revealed a 100% trisomy 18 placenta and a euploid child. Two FN results (both trisomy 21) were reported to the laboratory following amniocentesis due to other indications. For the sex chromosome aneuploidies XXX, XXY, and XYY, 7 of the 14 high-risk calls were within the follow-up cohort. Clinical follow-up revealed 4 cases with known outcomes: 2 TP (1 XXX, 1 XXY) and 2 FP (both XXX).