A multigravida with previous 2 normal deliveries presents with unstable lie of the fetus at 34 weeks gestation. What could be the most probable cause?

Ans. is a, i.e. Placenta previaRef. Dutta Obs. 7/e, p 397The presenting female is multipara with previous 2 normal deliveries and unstable lie.Lie refers to the relationship between the longitudinal axis of the fetus to that of the mother which may be longitudinal transverse or oblique.Unstable lie refers to the frequent changing of fetal lie and presentation even beyond 36th week of pregnancy.Contributing factors:Pelvicinletcontractureand/orfetalmacrosomiaPelvictumors Grandmultipara(M/Ccause)PlacentapreviaPolyhydramnios [?][?][?][?][?][?][?][?][?] -PreventengagementsUterine abnormalities (e.g. bicornuate uterus or uterine fibroids)Fetal anomaly (e.g. tumors of the neck or sacrum, hydrocephaly, abdominal distension).Coming to the question- patient is a multigravida with previous 2 normal deliveries:As history of normal delivery is present, it rules out uterine anomaly.There are no signs and symptoms suggestive of pelvic tumor.Oligohydramnios does not cause unstable lie, it is caused by polyhydramnios.Thus in this patent most probable cause of unstable lie is placenta previa.Note: M/C cause of fetal death in unstable lie is cord prolapse.