The Quadruple Marker Test is a prenatal screening conducted between the 15th and 20th weeks of pregnancy. It measures four key substances in the mother's blood: <strong data-start="236" data-end="263">alpha-fetoprotein (AFP), <strong data-start="265" data-end="303">human chorionic gonadotropin (hCG), <strong data-start="305" data-end="335">unconjugated estriol (uE3), and <strong data-start="341" data-end="354">inhibin A. This combination enhances the detection accuracy of potential fetal conditions such as <strong data-start="443" data-end="460">Down syndrome, <strong data-start="462" data-end="476">trisomy 18, and <strong data-start="482" data-end="505">neural tube defects. While it does not diagnose these conditions, the test helps estimate the likelihood of abnormalities, guiding healthcare providers and parents on whether further diagnostic testing may be needed. The Quadruple Marker Test is a valuable tool for informed prenatal care and early intervention planning.