Pathophysiology of pregnancy-associated acute kidney injury.

Pregnancy-associated acute kidney injury (PrAKI) remains a major contributor to maternal and fetal morbidity worldwide, with an estimated incidence of 40-100 per 10 000 pregnancies. PrAKI is substantially more prevalent in low- and middle-income countries. Unlike AKI episodes unrelated to pregnancy, PrAKI arises in a unique physiological context characterized by haemodynamic adaptation, immune tolerance, hormonal modulation, and the presence of the fetal-placental unit. These pregnancy-specific factors alter renal reserve, endothelial stability, and inflammatory responsiveness. The pathogenesis of PrAKI is multifactorial. Haemodynamic vasodilation and increased glomerular filtration rates during pregnancy reduce renal functional reserve, rendering the kidney vulnerable to hypovolemia and sepsis. Placental ischemia drives the release of antiangiogenic factors, particularly soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin, causing systemic endothelial dysfunction and glomerular endotheliosis. Disruption of immune tolerance and complement regulation further contributes to microangiopathy and autoimmune-mediated renal injury. Structural urinary tract changes, metabolic stressors, and maternal comorbidities amplify susceptibility. Beyond the index event, PrAKI has lasting consequences. Maladaptive renal repair promotes chronic kidney disease and long-term cardiovascular risk, while fetal exposure to uremic toxins and placental dysfunction contribute to intrauterine growth restriction, prematurity, and reduced nephron mass with lifelong cardio-renal implications. Understanding the pathophysiology of PrAKI, particularly endothelial, immunologic, and placental interactions, has direct diagnostic and therapeutic implications, including the use of angiogenic biomarkers and targeted haemodynamic strategies. Future research must prioritize molecular predictors, global registries, and mechanistic studies to reduce intergenerational kidney and cardiovascular disease.