In PP, the placental bed is situated in the lower
segment of the uterus. Severe post-partum hemorrhage
during cesarean section due to PP is still
one of the leading causes of maternal mortality
(19). In lower segment implantation, the muscles
surrounding the placental bed are inadequate for
contraction, retraction and thus bleeding ensues
(20). More blood vessels in PP employ more
blood vessels in placental bed and it seems that
angiogenic factors that affect placenta probably
could promote angiogenesis in placental bed; this
could explain sever postpartum bleeding in PP
cases.