<prompt> In the first trimester screening for Down syndrome which of the following test is to be done?Beta HCG, PAPPAMSAFP, PAPPAInhibin, PAPPAUnconjugated Estriol, PAPPAs  <response>: a. Beta HCG, PAPPARef: Nelsons 20e p 610-615Methods for Antenatal Screening for Down Syndrome - In 1st Trimester pg 79Screening methodDetection rateMaternal age Biochemical markers b-hCG, PAPPAQ70Maternal age Radiology USG- NT3mm80-83Combined test: Mat. Age Radiology USG-NT3mm82-87PAPPA is Pregnancy Associated Plasma Protein A 