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Inverted Pyramid of Care.
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Clin Lab Med 2016;36:305-17. pdf -
First-trimester ultrasound and biochemical markers of aneuploidy and the prediction of preterm or early preterm delivery.
Spencer K, Cowans NJ, Molina F, Kagan KO, Nicolaides KH.
Obstet Gynecol 2008;31:147-52.