Cesareans have become so commonplace--women are even electing to have them for convenience--that it's easy to think the surgery is no more perilous than a pedicure. But researchers from Britain's University of Oxford analyzed data on pregnancy and learned that one complication--out-of-control bleeding during or just after childbirth--is unsettlingly common in women who've had prior C-sections. The condition, which may arise because the placenta is likely to grow too low or through the wall of the womb after a cesarean, can be so risky ...