Desquamated fetal cells or lanugo from amniotic fluid enter maternal circulation and embolize to the pulmonary arterioles, mechanically block the pulmonary arterioles → increased pulmonary arterial pressure, right heart failure, and pulmonary edema
Entry of procoagulants (thromboplastin) from amniotic fluid into maternal circulation → diffuse intravascular coagulation
Entry of leukotrienes from amniotic fluid into maternal circulation → triggering of an immune response → pulmonary vasospasm, alveolar capillary damage (pulmonary edema), and hypotension