A nurse is reinforcing teaching about the purpose of quadruple screening for a client who is at 16 weeks of gestation. Which of the following statements should the nurse make?

A. "This test identifies indicators for birth defects.": The quadruple screen (quad screen) measures four maternal serum markers, alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol, and inhibin-A, to assess the risk of fetal neural tube defects and chromosomal abnormalities such as Down syndrome. B. "This test determines the sex of the fetus.": The quadruple screen does not determine fetal sex. Fetal sex can be identified through ultrasound or genetic testing, but the serum markers in the quad screen are not used for this purpose. C. "This test screens for gestational diabetes.": Gestational diabetes is screened with a glucose challenge test or oral glucose tolerance test, not the quadruple screen. The quad screen focuses on markers related to fetal development and chromosomal anomalies, not maternal glucose metabolism. D. "This test diagnoses fetal infection.": The quad screen does not detect infections in the fetus. Screening for fetal infections involves serologic testing, amniocentesis, or other targeted assessments depending on the suspected pathogen.