Table 1 Main characteristics of the patients included
From: Autoimmune disorders but not heparin are associated with cell-free fetal DNA test failure
|  | cfDNA not reportable n = 58 | cfDNA successful n = 295 | p-value |
|---|---|---|---|
Maternal age (years) | 37 (35.7–40.1) | 34 (29.6–37.1) | < 0.001 |
Maternal weight (kg) | 77 (60–90.3) | 64 (56–70) | < 0.001 |
Maternal height (cm) | 165 (161.8–171) | 165 (161–169) | 0.53 |
BMI | 29 (22.3–32.9) | 23.7 (20.7–25.9) | < 0.001 |
Ethnic group | Â | Â | 0.14* |
 Caucasian | 41 (70.7) | 237 (80.3) |  |
 Asian | 1 (1.7) | 13 (4.4) |  |
 Black or Caribbean | 7 (12.1) | 41 (13.9) |  |
 Other/unknown | 9 (15.5) | 4 (1.4) |  |
Cigarette smoker | 4 (6.9) | 1 (0.3) | Â |
Nulliparous | 22 (37.9) | 18 (6.1) | <Â 0.001 |
History of aneuploidy | 3 (5.2) | 9 (3.1) | Â |
Medical condition | |||
 Autoimmune disease | 7 (12.1) | 5 (1.7) | < 0.001 |
 Repeated vein thrombosis | 8 (13.8) | 3 (1.0) | < 0.001 |
 Other chronic condition | 5 (8.6) | 35 (11.9) | 0.65 |
Heparin received | 15 (25.9) | 20 (6.8) | <Â 0.001 |
Antiplatelet therapy | 9 (15.5) | 24 (8.1) | 0.11 |
Any other treatment receiveda | 14 (24.1) | 75 (25.4) | 0.96 |
Mode of conception | Â | Â | 0.83 |
 Spontaneous | 50 (86.2) | 248 (84.1) |  |
 Assisted | 8 (13.8) | 47 (15.9) |  |
Reason for referral | |||
 First-trimester screening | 40 (70.0) | 35 (11.9) |  |
 Second-semester screening | 10 (17.2) | 1 (0.3) |  |
 Maternal age | 4 (6.9) | 0 |  |
 History of aneuploidy | 4 (6.9) | 1 (0.3) |  |
 Ultrasound abnormalities | 0 | 19 (6.4) |  |
 First line screening | 0 | 239 (81.0) |  |