Pregnancy-related acute kidney injury at high altitude: a retrospective observational study in a single center

Abstract

Background Pregnancy-related acute kidney injury (Pr-AKI) is associated with maternal and fetal morbidity and mortality. There are few studies focusing on Pr-AKI at high altitude in the literature. Objectives to investigate the incidence, etiology, clinical features and maternal-fetal outcomes of Pr-AKI in women living at high altitude. Methods 6,512 pregnant women attending the Department of Obstetrics & Gynecology at local hospital from January 2015 to December 2018 were screened for Pr-AKI. Patients with serum creatinine above normal range(> 70umol/L) then underwent assessment to confirm the diagnosis of Pr-AKI. AKI was diagnosed and staged based on Kidney Disease Improving Global Outcomes(KDIGO) guideline. Individuals meeting the Pr-AKI criteria were recruited. Their clinical data were recorded and retrospectively analyzed. Results Pr-AKI was identified in 136/6512(2.09 %) patients. Hypertensive disorders of pregnancy(HDP) was the leading cause of Pr-AKI(35.3 %). 4(2.9 %) women died and the majority(86.1 %) had recovered renal function before discharge. Fetal outcomes were confirmed in 109 deliveries with gestational age ≥ 20 weeks. Pre-term delivery occurred in 30(27.3 %) cases and perinatal deaths in 17(15.5 %). The rate of low birth weight infant(LBWI) and intrauterine growth restriction(IUGR) was 22.0 and 10.9 % respectively. 16(14.5 %) infants were admitted to NICU after birth. Patients with HDP had a higher cesarean rate(56.3 %). More IUGR(25.0 %) and LBWI(37.8 %) were observed in their infants with a higher risk of admission to NICU(22.0 %). High altitude might have an adverse impact on HDP-related Pr-AKI patients with earlier terminated pregnancy and more stillbirth/neonatal death. Logistic regression models indicated that uncontrolled blood pressure, high altitude and advanced AKI were associated with adverse fetal outcomes in HDP-related Pr-AKI patients. Conclusions Pr-AKI was not rare in high-altitude regions and caused severe fetal morbidities and mortalities. Uncontrolled blood pressure, high altitude and advanced AKI were all risk factors for adverse fetal outcomes in Pr-AKI patients, especially for those with hypertensive disorders of pregnancy.

Causes and outcome of pregnancy related acute kidney injury

“…This finding is similar to another local study. 10 However the reported proportion of eclampsia in the current study is very low compared to many other studies where the stated percentages are 35%, 17 44.5%, 13 56%, 12 and 73%. 18 These high rates are basically due to reduction in number of cases of postpartum hemorrhage attributed to advanced health systems in contrast to high prevalence of obstetrical hemorrhage in the region of current study.…”

Effects of high altitude on renal physiology and kidney diseases

“…Although the specific causes of AKI were not identified, the authors suggested that acute systemic hypoxia and long-term renal hypoperfusion may have been the causes of renal injury ( Yijiang et al, 2013 ). In another study, high altitude was suggested to have an adverse influence on hypertensive disorders of pregnancy-related AKI, with earlier termination of pregnancy and a higher likelihood of stillbirth/neonatal death ( Li et al, 2021 ).…”

Pregnancy and Exercise in Mountain Travelers

“…Caution, careful consideration, and more research are needed for pregnant people traveling to high altitude. There are well-documented risks to low-altitude dwellers residing at high altitude for their entire pregnancy, including preeclampsia, eclampsia, hypertension of pregnancy, placenta previa, placental abruption, and preterm labor (4)(5)(6)(7)(8)(9)(10)(11). Fetal complications also are increased in this population, including small for gestational age, intrauterine growth retardation (IUGR), neonatal respiratory distress, pulmonary hypertension, and stillbirths but not congenital malformations (4,5,7,(9)(10)(11).…”

“…There are well-documented risks to low-altitude dwellers residing at high altitude for their entire pregnancy, including preeclampsia, eclampsia, hypertension of pregnancy, placenta previa, placental abruption, and preterm labor (4)(5)(6)(7)(8)(9)(10)(11). Fetal complications also are increased in this population, including small for gestational age, intrauterine growth retardation (IUGR), neonatal respiratory distress, pulmonary hypertension, and stillbirths but not congenital malformations (4,5,7,(9)(10)(11). Furthermore, in high-altitude dwellers, infant birth weight decreases with altitude, and lower birth weight is associated with greater health complications in infancy and beyond (9,12).…”