Framing Postpartum Hemorrhage as a Consequence of Human Placental Biology: An Evolutionary and Comparative Perspective

Abstract

Postpartum hemorrhage (PPH), the leading cause of maternal mortality worldwide, is responsible for 35 percent of maternal deaths. Proximately, PPH results from the failure of the placenta to separate from the uterine wall properly, most often because of impairment of uterine muscle contraction. Despite its prevalence and its well-described clinical manifestations, the ultimate causes of PPH are not known and have not been investigated through an evolutionary lens. We argue that vulnerability to PPH stems from the intensely invasive nature of human placentation. The human placenta causes uterine vessels to undergo transformation to provide the developing fetus with a high plane of maternal resources; the degree of this transformation in humans is extensive. We argue that the particularly invasive nature of the human placenta increases the possibility of increased blood loss at parturition. We review evidence suggesting PPH and other placental disorders represent an evolutionarily novel condition in hominins.

Exacerbated venous thromboembolism in mice carrying a protein S K196E mutation

“…Even today, as in ancient history, bleeding is the leading cause of maternal death linked to childbirth in the absence of modern medical care. 50 Thus, the PS-K196E, like the other 4 VTE-linked mutations, on balance may have benefited the Japanese population historically by reducing maternal death, although it increased VTE risk. If so, this PS-K196E Japanese mutation has been advantageous since its first occurrence after divergence of the Japanese population from other populations and during its subsequent adaptive evolution.…”

Condom Tamponade in the Management of Massive Obstetric Hemorrhage: An Experience at a Teaching Hospital

“…The inadequate uterine contraction, i.e, uterine atony, to sufficiently clamp the uterine vessels and stop bleeding 16 -is the most common cause of PPH. It can lead to rapid and severe hemorrhage and hypovolemic shock.…”

Women and the burden of human reproduction: An evolutionary perspective

“…The spiral arterioles, which have lost their muscle layer, cannot contract to close their lumen. 4 The mechanism of shutting the blood flow in the rich arterioles depends on retraction of the uterine muscle, which may fail.…”