Human Chorionic Gonadotropin (hCG) Measured in urine or blood blood test more sensitive Produced by syncytiotrophoblast of the placenta after implantation Used to detect pregnancy can see pregnancy on transvaginal ultrasound after hCG reaches 1,500-2,000 mIU/mL Urine Estriol Measured in maternal urine Produced by fetal adrenal gland maternal liver placenta Sign of fetal growth ↓ estriol is sign of fetal-maternal-placental dysfunction α-Fetoprotein (AFP) Measured in maternal serum ↑ AFP associated with open neural tube defects ↓ AFP associated with Down syndrome Lecithin/Sphingomyelin (L:S) Ratio Measured in amniotic fluid lecithin is a surfactant produced by fetal lungs used to determine maturity of fetal lungs L:S ratio > 2 indicates maturity L:S ratio < 2 administration of cortisol ↑ lecithin production login to view 1 more bullet thyroxine also ↑ lethicin production insulin ↓ production First Trimester Screen (10-13 weeks) Serum labs serum free β-hCG or total hCG login to view 3 more bullets pregnancy-associated plasma protein A (PAPP-A) login to view 3 more bullets Imaging nuchal translucency measurement login to view 2 more bullets Quadruple Screen (15-22 weeks) Test for aneuploidy hCG login to view 2 more bullets alpha fetoprotein (AFP) login to view 2 more bullets dimeric inhibin A login to view 2 more bullets unconjugated estriol login to view 2 more bullets