Kramer et al reported a doubling of the incidence of severe postpartum hemorrhage (PPH) over recent years (1999-2008), although were unable to explain the overall temporal trend despite analyzing traditional risk factors. An audit of 2 UK units, delivering more than 4000 babies per year, showed increases in PPH greater than 1000 mL, and PPH greater than 2000 mL, of greater than 500% (2003-2012).

Traditional risk factors (increased maternal age, parity, fetal macrosomia, etc) appeared to be less significant because many cases occurred in young, nulliparous women undergoing induction of labor that resulted in the delivery of an appropriate-for-gestational-age baby by cesarean section.

There is evidence for prepregnancy injuries to the myometrium resulting from physical efforts during defecation, which is endemic (>30%) in Western populations and excessive traction to the cervix during minor gynecologic procedures. Both injure uterine and tubal nerves in their course through the uterosacral ligaments, and both continue to increase in frequency in Western societies. There is also direct evidence for minor gynecological procedures causing adverse reproductive outcomes (eg, preterm labor) that may also result from prepregnancy denervatory injuries.

Whether injured uteri respond to oxytocic agents, prostaglandins, and, surgical maneuvers may be an important question in contemporary intrapartum care.