Pulmonary arterial hypertension
PAH defined as a mean pulmonary artery pressure >25 mm Hg is associated with up to 50% risk of
maternal mortality in pregnancy [38]. With targeted pulmonary vasodilator therapies such as inhaled
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iloprost or intravenous prostacyclin, there has been some improvement, but mortality still remains up
to 33% [39]. Death is often sudden a few days after delivery, and it occurs due to the combination of an
increase in systemic vascular resistance limiting cardiac output, thrombosis of distal pulmonary vessels
and the increased venous return from uterine auto-transfusion during contractions and from placental
auto-transfusion and release of caval compression after delivery.