Table 1 Characteristics of the 22,812 pregnancies screened
From: Prenatal reflex DNA screening for trisomies 21, 18, and 13
Median age (years) at estimated date of delivery (IQR) | 31 (28–35) |
Median maternal weight (kg) (IQR) | 64 (57–73) |
Median gestational age (weeks + days) at blood sample (IQR) | 12 + 5 (12 + 2–13 + 1) |
Ethnicity | |
Caucasian | 11,939 (52%) |
Black | 1,858 (8.1%) |
South Asian | 6,484 (28.4%) |
Oriental (East or South East Asian) | 962 (4.2%) |
Other | 1,569 (6.9%) |
Insulin-dependent diabetes | 87 (0.4%) |
In vitro fertilization | 791 (3.5%) |
Twins | 381 (1.7%) |
Monochorionic | 80 (21%) |
Dichorionic | 295 (77%) |
Unknown chorionicity | 6 (1.6%) |
Smoker | 1,222 (5.4%) |
Trisomy 21 (prevalence) | 73 (0.32%) |
Trisomy 18 (prevalence) | 25 (0.11%) |
Trisomy 13 (prevalence) | 8 (0.04%) |
All affected (prevalence) | 106 (0.46%) |
