This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pregnancy in Rh-negative Women, Subject name: Gynaecology & Obstetrics
All predisposes to isoimmunisation in a Rh-ve female except: 
Select and explain. 
A. Advanced maternal age, B. Antepartum hemorrhage, C. Cesarean section, D. Post-dated pregnancy
A: Advanced maternal age
Answer: A: Advanced maternal age 
Explanation: Ans. is a, i.e. Advanced maternal ageRef. Dutta Obs. 7/e, p 332; Textbook of Obs. Sheila Balakrishnan 1/e, p 369Conditions predisposing to isoimmunization in Rh -ve femaleAbortion Q, ectopic pregnancy, molar pregnancyChorionic villous sampling QCordocentesisTraumaAmniocentesis QAntepartum hemorrhageAttempted version QVaginal deliveryManual removal of placentaCesarean sectionStudies show that there is continuous fetomaternal bleed occurring throughout normal pregnancies. During normal pregnancy, fetal red cells cross the placenta in 5% patients during first trimester and in 40-47% patients by the end of third trimester.So it is not advisable to go beyond the expected date of pregnancy in Rh negative females carrying Rh +ve fetus. Hence post-dated pregnancy is another risk-factor for isoimmunization.