All predisposes to isoimmunisation in a Rh-ve female except:

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.