Abruptio placentae occurs in all except:
Abruptio placenta is premature separation of normally situated placentaQ resulting in hemorrhage.
Risk factors:

Increased maternal age - Increased parity
Pre eclampsia - Chronic hypertension
Preterm ruptured membranes pregnancy - Sudden uterine decompression as in hydramnios and twin
Cigarette smoking - Thrombophilia
Cocaine abuse - Previous abruption
External trauma - Folic acid deficiency
Uterine leiomyoma

My – My- I pity all of you out there as you have to memorise so many lists (not only in gynae, obs but in other subjects as well). Even I have gone through the same phase. Friends I had devised a simple method to learn these lists. For some lists, I used to draw diagrams and then at the time of exam that diagram was reproduced in my mind. Try it out for yourself. e.g.
Smokers
Alcoholics
PET
Folic acid deficiency
Alcoholics