This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
Prophylactic anti-D immunoglobulin is given to Rh-negative pregnant women antenatally at 
Select and explain. 
A. 20 weeks, B. 24 weeks, C. 28 weeks, D. 32 weeks
C: 28 weeks
Answer: C: 28 weeks 
Explanation: Anti-D immune globulin is given prophylactically to all Rh D-negative, unsensitized women at approximately 28 weeks, and a second dose is given after delivery if the infant is Rh D-positive. Before the 28-week dose of anti-D immune globulin, repeat antibody screening is recommended to identify individuals who have become alloimmunized.Provision of anti-D immune globulin at 28 weeks gestation reduces the third-trimester alloimmunization rate from approximately 2 percent to 0.1 percent (Ref: William's Obstetrics; 25th edition)