If Amneocentesis test is NORMAL, why, for what reasons did my double marker blood report show low values of free beta hcg= 0.35 MoM, and PAPP-A =0.19 MoM at 12 weeks??? because of which my double marker report showed high risk for T18= 1:29 and T13= 1:256 Few other measurements at 12 weeks were,  CRL=54.6mm, NT=1.4mm, my age= 34years, my height=160cm, my weight= 67 kg, Past history i had spontaneous miscarriage (2months) in Feb & conceived in March. I was taking folic acid and iron supplements in Feb.