TABLE 1.

Demographic data of the study population (Down screening, Chiang Mai, Thailand, 2016–2021).

Characteristics	Total (n = 39,740)	Down syndrome pregnancy (n = 74)	Normal pregnancy (n = 39,666)	p-value
Age (years)	28.66 ± 5.67	32.23 ± 6.57	28.66 ± 5.65	<0.001*
GA at sample collection (weeks)	15.8 ± 1.4	15.7 ± 1.3	15.8 ± 1.3	0.211
Maternal weight (kg)	58.6 ± 11.9	59.4 ± 11.9	58.6 ± 11.9	0.390
Nulliparous (%)	56.3%	59.3%	56.3%	0.332
GA at delivery (weeks)	38.3 ± 1.7	23.7 ± 7.5	38.3 ± 1.6	<0.001
Birth weight (gm)	2,888 ± 619	2,892 ± 611	582 ± 1,089	<0.001

Value presented as mean ± SD. p-value corresponds to independent t-test.