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. 2016 Nov 7;355:i5789. doi: 10.1136/bmj.i5789

Table 1.

Overview of population characteristics

Characteristics Distribution Data available
Mean (SD) maternal age (years)* 30.8 (4.8) 32 160 (100.0)
Ethnicity (No (%)): 21 536 (67.0)
 European* 19 478 (90.4)
 Mediterranean† 879 (4.1)
 Black Creole‡ 168 (0.8)
 Asian§ 85 (0.4)
 Hindustani 66 (0.3)
 Other 860 (4.0)
Parity (No (%)): 21 579 (67.1)
 Nulliparous 9712 (45.0)
 Multiparous 11 867 (55.0)
Mean (SD) gestational age at sampling (weeks+days) 276 (06) 21 579 (67.1)
Median (range) cell-free fetal DNA level (genome equivalents/mL)c 46.6 (1.5-868.5) 13 076 (40.7)

*Not including Mediterranean countries.

†All countries surrounding the Mediterranean Sea.

‡Black Creole includes all black people.

§Asian included all Asian countries, with the exception of people of Hindustani descent.