This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Obs), Subject name: Gynaecology & Obstetrics
Rh isoimmunisation in which trimester 
Select and explain. 
A. 10-12 weeks, B. 30-32 weeks, C. 36 weeks, D. Immediately after delivery
B: 30-32 weeks
Answer: B: 30-32 weeks 
Explanation: (B) 30-32 weeks> Because of its short half-life, Rh IgG routinely is administered once at 28-32 weeks' gestation and again within 72 hours after birth to all Rh-negative pregnant females as a part of routine prenatal care.