Pinnington TR, Arthan J, Komoltri C, Chanprapaph P. Accuracy of the Combined First Trimester Down Syndrome Screening Test and the Optimum Range of the Cut-off Point for Intermediate-risk Identification: Twelve years’ experience . Thai J Obstet Gynaecol [internet]. 2024 Jul. 1 [cited 2026 Oct. 12];32(4):269-77. available from: https://he02.tci-thaijo.org/index.php/tjog/article/view/264887