This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in Obstetrics, Subject name: Gynaecology & Obstetrics
An HIV positive, 36 years old female on ART needs counseling. Which of the following 1st trimester markers of Down syndrome would be affected by HIV: 
Select and explain. 
A. b-hCG, B. PAPP-A, C. NT, D. All of the above
A: b-hCG
Answer: A: b-hCG 
Explanation: Ans. is a, i.e. b-hCGRef. Fernando Arias 4/e, p 4In women with HIV:b-hCG levels in women who are HIV positive and are on treatment have been shown to have a lower value than women without HIV and those with HIV not receiving treatment. In contrast PAPP- A levels and NT are not affected by HIV status.