Acute Kidney Injury in Pregnancy: The Changing Landscape for the 21st Century

Miscarriage-Related Acute Kidney Injury: A Case Report

Background

Pregnancy-related acute kidney injury (Pr-AKI) is associated with significant maternal and fetal morbidity and mortality, with a three- to four-fold increase in perinatal mortality. Pr-AKI can arise from various obstetric complications, such as hyperemesis gravidarum, septic abortion, hypertensive disorders of pregnancy, pyelonephritis, and antiphospholipid antibody syndrome. Therefore, early diagnosis and appropriate intervention, including the identification of the underlying etiology, are important to effectively manage Pr-AKI. Therefore, we report a case of Pr-AKI after early miscarriage in a patient without hyperemesis gravidarum or septic abortion whose renal function gradually improved postoperatively for miscarriage.

Case Presentation

A 34-year-old primigravid woman was referred to us for perinatal management at 6 weeks of gestation. Unfortunately, she was diagnosed with miscarriage 1 week later. The patient had no history of hyperemesis gravidarum or septic abortion; however, she developed oliguria, and her serum creatinine and blood urea nitrogen levels were abnormally increased. Consequently, she underwent a renal biopsy to evaluate renal dysfunction, which indicated tubulointerstitial damage. The patient also underwent manual vacuum aspiration for a miscarriage. Postoperatively, her urine output increased, and her renal function improved. She was determined to have experienced Pr-AKI due to her miscarriage.

Conclusion

Our patient had Pr-AKI after a miscarriage in the absence of other causes. This case report highlights the presence of unknown causes of Pr-AKI, warranting further research for the development of preventive interventions.

Acute Kidney Injury in Pregnancy: A Prospective Study

INTRODUCTION

When acute kidney damage occurs during pregnancy, it poses a difficult clinical problem. One of the main causes of maternal and fetal morbidity and death is pregnancy-related acute kidney injury (AKI), a significant obstetric complication characterized by a fast deterioration in renal function and several subsequent clinical problems. The objective of the study is to analyze the etiological factors, clinical manifestations, and maternal and fetal outcomes of AKI during pregnancy.

MATERIALS AND METHODS

This prospective observational research involved patients hospitalized in the General Medicine and Obstetrics and Gynecology departments at Indira Gandhi Institute of Medical Sciences, Patna, for a year (October 2021 to September 2022) due to obstetric difficulties resulting in acute renal damage.

RESULTS

The study included 62 patients with a mean age of 25.08±4.25 years. The majority of patients in our study were aged 18-25 years (38, 61.3%), followed by 26-30 years (19, 30.6%) and >30 years (5, 8.1%). The majority of patients in our study were non-booked (52, 83.9%) and presented as emergency cases, whereas 10 (16.1%) patients had booked. In addition, 34 (54.8%) patients were primigravida, while 28 (45.1%) were multigravida. There were 25 patients in their third trimester (40.3%), 19 who were postpartum (30.6%), 10 who were post-abortion (16.1%), and eight in their second trimester (12.9%). Upon admission, the majority of the patients showed signs of oliguria, accounting for 45 cases (72.6%). This was followed by nine cases of abnormal kidney function (14.5%) and eight cases of anuria (12.9%). Among the other symptoms, fever was observed in 25 cases (40.32%), whereas breathlessness increased to 15 cases (24.19%), edema was present in 14 cases (22.58%), vomiting and altered sensorium were observed in four cases (6.45%), abdominal pain was observed in three cases (4.83%), and burning micturition was observed in two cases (3.22%). The most common causes of AKI in pregnancy in the present study were puerperal sepsis (18 cases, 29.0%), followed by preeclampsia/eclampsia (14 cases, 22.6%), hemorrhagic shock (10 cases, 16.1%), septic abortion (six cases, 9.7%), hyperemesis gravidarum (four cases, 6.5%), acute fatty liver of pregnancy (three cases, 4.8%), disseminated intravascular coagulation (three cases, 4.8%), drug-induced sepsis (two cases, 3.2%), and urosepsis (two cases, 3.2%). Modes of delivery in this study were normal vaginal delivery (32 cases, 51.6%), lower segment cesarean section (21 cases, 33.9%), dilation and evacuation (seven cases, 11.3%), and total hysterectomy (two cases, 3.2%). Hemodialysis was performed in 39 patients (62.9%), and 51 (82.3%) received blood transfusions. The mean systolic and diastolic BP (mmHg) were 111.37±22.60 and 71.40±18.88, respectively. Maternal outcome data revealed that 48 (77.4%) women had fully recovered, eight (12.9%) had not recovered, 43 (69.4%) were lost to follow-up, and two (3.2%) had died. Neonatal outcomes in the present study were as follows: live birth, 43 (69.4%); abortion, eight (12.9%); intrauterine death of the fetus, five (8.1%); and neonatal mortality, six (9.7%).

CONCLUSION

The diagnosis and treatment of AKI during pregnancy is a significant challenge for the treating physician because of the pathophysiological changes that occur during pregnancy, the variability of symptoms, and the fact that clinical and laboratory features may occasionally overlap.

Causes and outcome of pregnancy related acute kidney injury

Objective

To determine frequencies of causes and renal outcomes of pregnancy related acute kidney injury.

Method

This descriptive case series study was conducted in Nephrology unit of a tertiary care hospital of Peshawar, from 1st August 2021 to 31st July 2022.A total of 100 patients with acute kidney injury secondary to obstetric conditions were enrolled via non-probability consecutive sampling technique. While patients with pre-existing renal disease, those with renal stones, or having bilateral small kidneys on ultrasound were excluded from the study. Patients were followed till 12 weeks postpartum period. Underlying obstetrical causes and outcome at 12 weeks postnatal period were determined.

Results

The mean age of sample of 100 cases was 29.29 ± 6.45. Mean serum creatinine at presentation was 6.5± 3.13. Majority of patient, 89% were multigravidas. Seventy eight percent patients required hemodialysis. Primary postpartum hemorrhage remained the commonest underlying cause of pregnancy related acute kidney injury in this study. The frequency of persistent renal failure in Pr-AKI (pregnancy related acute kidney injury) in this study was 14%. In about 66% of cases complete recovery occurred. All the underlying obstetrical causes, when adjusted for age, gravidity, place and mode of delivery, had no association with persistent renal failure.

Conclusion

Primary postpartum hemorrhage is the predominant cause of pregnancy related acute kidney injury. By the end of 12 weeks postpartum, two third patients recover completely from pregnancy related acute renal injury.

Characteristics and Outcomes of Patients With Pregnancy-Related End-Stage Kidney Disease

Importance

The incidence of pregnancy-related acute kidney injury is increasing and is associated with significant maternal morbidity including progression to end-stage kidney disease (ESKD). Little is known about characteristics and long-term outcomes of patients who develop pregnancy-related ESKD.

Objectives

To examine the characteristics and clinical outcomes of patients with pregnancy-related ESKD and to investigate associations between pre-ESKD nephrology care and outcomes.

Design, Setting, and Participants

This was a cohort study of 183 640 reproductive-aged women with incident ESKD between January 1, 2000, and November 20, 2020, from the US Renal Data System and maternal data from births captured in the US Centers for Disease Control and Prevention publicly available natality data. Data were analyzed from December 2022 to June 2023.

Exposure

Pregnancy-related primary cause of ESKD, per International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes reported at ESKD onset by the primary nephrologist on Centers for Medicare and Medicaid Services form 2728.

Main Outcomes Measures

Multivariable Cox proportional hazards and competing risk models were constructed to examine time to (1) mortality, (2) access to kidney transplant (joining the waiting list or receiving a live donor transplant), and (3) receipt of transplant after joining the waitlist.

Results

A total of 341 patients with a pregnancy-related primary cause of ESKD were identified (mean [SD] age 30.2 [7.3]). Compared with the general US birthing population, Black patients were overrepresented among those with pregnancy-related ESKD (109 patients [31.9%] vs 585 268 patients [16.2%]). In adjusted analyses, patients with pregnancy-related ESKD had similar or lower hazards of mortality compared with those with glomerulonephritis or cystic kidney disease (adjusted hazard ratio [aHR], 0.96; 95% CI, 0.76-1.19), diabetes or hypertension (aHR, 0.49; 95% CI, 0.39-0.61), or other or unknown primary causes of ESKD (aHR, 0.60; 95% CI, 0.48-0.75). Despite this, patients with pregnancy-related ESKD had significantly lower access to kidney transplant compared with those with other causes of ESKD, including (1) glomerulonephritis or cystic kidney disease (adjusted subhazard ratio [aSHR], 0.51; 95% CI, 0.43-0.66), (2) diabetes or hypertension (aSHR, 0.81; 95% CI, 0.67-0.98), and (3) other or unkown cause (aSHR, 0.82; 95% CI, 0.67-0.99). Those with pregnancy-related ESKD were less likely to have nephrology care or have a graft or arteriovenous fistula placed before ESKD onset (nephrology care: adjusted relative risk [aRR], 0.47; 95% CI, 0.40-0.56; graft or arteriovenous fistula placed: aRR, 0.31; 95% CI, 0.17-0.57).

Conclusion and Relevance

In this study, those with pregnancy-related ESKD had reduced access to transplant and nephrology care, which could exacerbate existing disparities in a disproportionately Black population. Increased access to care could improve quality of life and health outcomes among these young adults with high potential for long-term survival.

Incidence of Pregnancy-Related Acute Kidney Injury in a Low Resource Setting: A Prospective Study

Background

Pregnancy-related acute kidney injury (PRAKI) is a common cause of AKI globally. The incidence and burden of PRAKI are still high in low and middle-income countries (LMICs) especially in Africa due to limited access to optimal obstetric care, late diagnosis, and referral. The study aimed to determine the incidence and aetiologies of PRAKI among women in the peripartum period in two government hospitals in Nigeria.

Methodology

This was a prospective study where serum creatinine was measured among pregnant women presenting in labour at 0-hour, 6 hour, 12 hour, 24 hour, 48 hour and 7 days post-delivery. AKI was defined using the Kidney Disease Improving Global Outcome criteria. Binary logistic regression was used to determine predictors of PRAKI.

Results

The mean age of the 162 pregnant women who completed the study was 30.05±1.28 years. The incidence of AKI use was 22.2%. The aetiologies of PRAKI were obstetric haemorrhage (66.7%), eclampsia (19.4%), and sepsis (13.9%). Seventeen (47.2%) patients had Stage 1 PRAKI, 12 (33.3%) had Stage 2 PRAKI, while seven (19.4%) had Stage 3 PRAKI. Factors significantly associated with PRAKI were parity (p=<0.001), caesarean section (p=<0.001), excess blood loss (p=<0.001), and prolonged duration of labour (p=0.002).

Conclusion

PRAKI occurred in 1 out 5 pregnant women in the peripartum period. Obstetric haemorrhage, sepsis, and eclampsia which are preventable or treatable are common major aetiologies of PRAKI. PRAKI is more associated with multi-parity, caesarean delivery, haemorrhage, and prolonged duration of labour. Optimal ante-natal care, health education, and prompt diagnosis and management of obstetric complications will reduce the incidence in Nigeria.

Clinical characteristics and prognosis of pregnancy-related acute kidney injury: a case series study

OBJECTIVE

Acute kidney injury (AKI) seriously affects the health of both pregnant women and fetuses. This study aimed to investigate the clinical characteristics and prognosis of pregnancy-related AKI (PR-AKI).

METHODS

This case series study enrolled pregnant women with PR-AKI admitted to the surgical intensive care unit of Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine between January 2010 and December 2020.

RESULTS

Thirty-one PR-AKI patients were enrolled with a mean age of 29.16 ± 4.97 years. Seventeen pregnant women (54.84%) had complete recovery of renal function, 5 (16.13%) had partial recovery of renal function, 2 (6.45%) patients had no renal function improvement, and 7 (22.58%) died. Among the 31 patients with 35 fetuses, 25 (80.6%) pregnant women had poor fetal outcomes, including 5 cases of stillbirths, 5 neonatal asphyxia, 18 premature births, 10 low birth weight, and 8 deficient birth weight infants. Compared to cases with good fetal outcomes, cases with poor fetal outcomes had significantly shorter gestational weeks (39.26 ± 1.53 vs. 31.62 ± 5.50, P = 0.002), lower platelet count (217.13 ± 122.87 vs. 90.24 ± 84.88, P = 0.005), lower hemoglobin (94.19 ± 13.21 vs. 74.48 ± 20.78, P = 0.036), higher blood urea nitrogen (11.87 ± 4.28 vs. 19.47 ± 10.98, P = 0.013), and higher uric acid (262.41 ± 167.00 vs. 586.87 ± 144.52, P < 0.001).

CONCLUSIONS

The maternal renal function of women with PR-AKI might improve after treatment, but occurrence rates of adverse fetal outcomes were still high.

Pregnancy in Chronic Kidney Disease: Acute Kidney Injury in Pregnant Women and Management of Chronic Kidney Disease in the Pregnant Patient

Women pursue pregnancy with comorbidities such as hypertension and kidney disease, necessitating primary care physicians to remain up to date with current clinical practice. Hypertensive disorders of pregnancy pose risks to the pregnancy and to the woman in the short and long term. These risks and their management are detailed in this review. Normally, pregnancy is associated with hemodynamic and kidney-specific changes. Here the authors discuss these changes and review the impact and management of pregnancy-related acute kidney injury, chronic kidney disease, and dialysis in pregnant patients. Kidney transplant recipients may experience return of fertility and require counseling to improve outcomes.

Dialysis in Pregnancy: An Update Review

Chronic kidney disease and end-stage kidney disease (ESKD) are important public health problems with increased rates of morbidity, mortality, and social costs. Pregnancy is rare in patients with ESKD, with reduced fertility rates in women undergoing dialysis. Although current advances have led to an increase in live births in pregnant dialysis patients, this modality still has an increased risk of multiple adverse events in pregnant women. Despite these existing risks, large-scale studies investigating the management of pregnant women on dialysis are lacking, resulting in the absence of consensus guidelines for this patient group. In this review, we aimed to present the effects of dialysis during pregnancy. We first discuss pregnancy outcomes in dialysis patients and the development of acute kidney injury during pregnancy. Then, we discuss our recommendations for the management of pregnant dialysis patients, including the maintenance of pre-dialysis blood urea nitrogen levels, the ideal frequency and duration of hemodialysis sessions, as well as the modality of renal replacement therapies, the difficulty of maintaining peritoneal dialysis in the third trimester of pregnancy, and optimization of prepregnancy modifiable risk factors. Finally, we present our recommendations for future studies investigating dialysis among pregnant patients.

Ethnic disparities in pregnancy-related acute kidney injury in a United Kingdom population

BACKGROUND

The incidence of acute kidney injury in pregnancy (P-AKI) is rising and is associated with detrimental maternal and foetal outcomes. Ethnic disparities in pregnancy outcomes are well recognized, with females who identify as Black or Asian being more likely to die during pregnancy compared to females who identify as White ethnicity.

METHODS

This study reports rates of P-AKI and associated risk factors in pregnant females of different ethnicities. All pregnancies were recorded between 2016 and 2020. AKI episodes were identified using electronic alerts. Ethnicity, AKI stage (1-3), obstetric outcomes and risk factors for P-AKI (chronic hypertension, pregnancy-induced hypertension and pre-eclampsia, and haemorrhage) were assessed.

RESULTS

There were 649 P-AKI episodes from 16,943 deliveries (3.8%). Black females were more likely to have P-AKI (5.72%) compared to those who were White (3.12%), Asian (3.74%), mixed ethnicity (2.89%) and Other/Not Stated (3.10%). Black females, compared to White females, were at greater risk of developing P-AKI if they had haemorrhage requiring blood transfusion (OR 2.44, 95% CI 1.31,4.54; p < 0.001) or pregnancy-induced hypertension (OR 1.79, 95% CI 1.12, 2.86; p < 0.001). After adjusting for risk factors, Black females had increased risk of developing P-AKI (OR 1.52, 95% CI 1.22, 1.80; p < 0.001) compared to White females. Black females were at increased risk of developing P-AKI compared to White females. Mode of delivery, pregnancy-induced hypertension and haemorrhage are likely to have contributed. The increased risk persists despite accounting for these variables, suggesting that other factors such as socioeconomic disparities need to be considered.

CONCLUSIONS

The incidence of P-AKI is likely higher than previously stated in the literature. However, caution must be exercised, particularly with AKI stage 1, as the KDIGO system is not validated in pregnancy and gestational changes in renal physiology need to be considered. Pregnancy-specific AKI definitions are needed.

Pregnancy-related acute kidney injury in the African continent: where do we stand? A systematic review

BACKGROUND

Pregnancy-Related Acute kidney injury (PR-AKI) is a global health problem with substantial maternal and fetal morbidity and mortality. However, little is known about the current situation in the developing world including African countries. Africa is the poorest continent per capita, and women from Sub-Saharan Africa alone account for 66% of the estimated global maternal deaths from preventable obstetric causes.

METHODS

OBJECTIVE: To review the literature on the clinical profile, maternal and renal outcomes of women with PR-AKI in the African continent.

SEARCH STRATEGY

Medline, ISI Web of Science, Scopus, and Cochrane library were searched in February 2022, using the MeSH terms and text key words: "pregnancy", "pregnant", "acute kidney injury", "acute renal insufficiency", "acute renal injury", "acute renal failure", and "Africa".

SELECTION CRITERIA AND DATA COLLECTION

Studies from African countries which reported maternal and renal outcomes in women with PR-AKI during pregnancy or postpartum were included. Editorials, short communications, and case reports were excluded. The study quality was assessed using the NHLBI tool. Data extraction was done using predefined data fields.

RESULTS

A total of 167 studies were evaluated, of which 14 studies from seven African countries met the inclusion criteria. Preeclampsia, obstetric hemorrhage, and sepsis represented the main causes of PR-AKI. Maternal mortality ranged between 0 and 34.4%. Although the majority of women needed ICU admission and hemodialysis, renal recovery occurred in 53.1-90% of patients. Perinatal mortality has been reported to be 1.5-60.5% in the included studies.

AUTHORS' CONCLUSIONS

PR-AKI in Africa represents the second leading cause of AKI. Limited access to obstetric care, late referral, and late diagnosis of women with risks for PR-AKI hinder the curtailment of the problem. Provision of health care facilities with adequately trained personnel and implementation of preventive strategies will be of great value in decreasing the magnitude of the problem.

Etiology of Pregnancy-related Acute Kidney Injury among Obstetric Patients in India: A Systematic Review

Background

Pregnancy-related acute kidney injury (PRAKI) is an important cause of fetomaternal mortality and morbidity in developing countries. We undertook a systematic review to identify the causes of PRAKI among obstetric patients in India.

Materials and methods

We systematically searched PubMed, MEDLINE, Embase, and Google Scholar using appropriate search terminology between 1 January 2010 to 31 December 2021. Studies reporting the etiology of PRAKI among obstetric patients (pregnant and within 42 days postpartum) in India were included for evaluation. Studies done in any other geographical location besides India were excluded. We also excluded studies done in any one trimester or any specific subgroup of patients [e.g., postpartum acute kidney injury (AKI), postabortal AKI]. A five-point questionnaire was used to assess the risk of bias in included studies. The results were synthesized as per preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

Results

A total number of 7 studies with 477 participants were included for analysis. All were single-center descriptive observational studies either done in tertiary care public or private hospitals. Sepsis (mean, 41.9%; median, 49.4%; and range, 6-56.1%) was the most common cause of PRAKI followed by hemorrhage (mean, 22.1%; median, 23.5%; and range, 8.3-38.5%) and pregnancy-induced hypertension (mean, 20.9%; median, 20.7; and range, 11.5-39%). Among these seven studies, five were of moderate quality, one was of high quality, and another one was of low quality. Our study is limited due to the lack of consensus definition of PRAKI in literature and heterogeneity in reporting methods. Our study highlights the need for a structured reporting format for PRAKI to understand the true disease burden and take control measures.

Conclusion

There is a moderate quality of evidence to suggest that sepsis followed by hemorrhage and pregnancy-induced hypertension are the commonest causes of PRAKI in India.

How to cite this article

Gautam M, Saxena S, Saran S, Ahmed A, Pandey A, Mishra P, et al. Etiology of Pregnancy-related Acute Kidney Injury among Obstetric Patients in India: A Systematic Review. Indian J Crit Care Med 2022;26(10):1141-1151.

Pregnancy-Associated Acute Kidney Injury in Low-Resource Settings: Progress Over the Last Decade

Despite immense global effort, the maternal mortality rate in low-resource settings remains unacceptably high. Globally, this reflects the grave inequalities in access to health and reproductive services. Pregnancy-associated acute kidney injury (PRAKI) is an independent risk factor for mortality. The reported incidence of PRAKI in low- and middle-income countries is higher than that of high-income countries (4%-26% versus 1%-2.8%, respectively). Hypertensive disorders are now the leading cause of PRAKI in many regions, followed by hemorrhage and sepsis. PRAKI in low-resource settings carries a high mortality for both mother and child. Outcome studies suggest that PRAKI is associated with residual kidney dysfunction and may lead to dialysis dependence. This can be a death sentence in many regions with limited kidney replacement therapy. This review will summarize data on PRAKI on the African, Latin American, and Asian continents over the past decade. It will include the progress in published data, mortality, and treatment interventions and provide recommendations for the next decade.

Kidney-Placenta Crosstalk in health and disease

Organ crosstalk allows the interaction between systems to adapt to a constant changing environment, maintaining homeostasis. The process of placentation and the new hormonal environment during pregnancy trigger physiological changes that modulate kidney function to control extracellular volume, acid-base balance, and filtration of metabolic waste products. The bidirectional communication means that acute or chronic dysfunction of one organ can compromise the other. Abnormal placentation in pregnancy-related hypertensive disorders such as pre-eclampsia and HELLP (haemolysis, elevated liver enzymes and low platelet count) syndrome leads to the release of antiangiogenic factors that may cause kidney injury (thrombotic microangiopathy, glomeruloendotheliosis, mesangiolysis and vasoconstriction of peritubular vessels). These hypertensive disorders are a key cause of kidney injury in gestation, which increases maternal morbi-mortality and adverse foetal outcomes. Conversely, prior kidney injury or causes of kidney injury (diabetes, lupus, glomerulonephritis or other form of chronic kidney disease) increase the risk of developing hypertensive pregnancy disorders, providing a baseline higher risk. Inherited kidney diseases are a special concern, given the potential for genetic predisposition to kidney disease in the foetus. Understanding the bidirectional potential for compromise from placenta to kidney and vice versa provides a better framework to limit damage to both organs and improve maternal and foetal outcomes.

Acute kidney injury during pregnancy in kidney transplant recipients

Pregnancy-related acute kidney injury (AKI) is a public health problem and remains an important cause of maternal and fetal morbidity and mortality. The incidence of pregnancy-related AKI has increased in developed countries due to increase in maternal age and higher detection rates. Pregnancy in women with kidney transplants is associated with higher adverse outcomes like preeclampsia, preterm births, and allograft dysfunction, but limited data exist on causes and outcomes of pregnancy-related AKI in the kidney transplant population. Diagnosis of AKI during pregnancy remains challenging in kidney transplant recipients due to lack of diagnostic criteria. Management of pregnancy-related AKI in the kidney transplant population requires a multidisciplinary team consisting of transplant nephrologists, high-risk obstetricians, and neonatologists. In this review, we discuss pregnancy-related acute kidney injury in women with kidney transplants, etiologies, pregnancy outcomes, and management strategies. This article is protected by copyright. All rights reserved.

Pr-AKI: Acute Kidney Injury in Pregnancy – Etiology, Diagnostic Workup, Management

Despite significant improvements in inpatient and outpatient management, pregnancy-related acute kidney injury (Pr-AKI) remains an important risk factor for early and late maternal and fetal morbidity and mortality. There is a discrepancy between the incidence of Pr-AKI in developing and in developed countries, with the former experiencing a decrease and the latter an increase in Pr-AKI in recent decades. Whereas septic and hemorrhagic complications predominated in the past, nowadays hypertensive disorders and thrombotic microangiopathy are the leading causes of Pr-AKI. Modern lifestyles and the availability and widespread use of in-vitro fertilization techniques in industrialized countries have allowed more women of advanced age to become pregnant. This has led to a rise in the percentage of high-risk pregnancies due to the disorders and comorbidities inherent to or accompanying aging, such as diabetes, arterial hypertension and preexisting chronic kidney disease. Last but not least, the heterogeneity of symptoms, the often overlapping clinical and laboratory characteristics and the pathophysiological changes related to pregnancy make the diagnosis and management of Pr-AKI a difficult and challenging task for the treating physician. In addition to general supportive management strategies such as volume substitution, blood pressure control, prevention of seizures or immediate delivery, each disease entity requires a specific therapy to reduce maternal and fetal complications. In this review, we used the current literature to provide a summary of the physiologic and pathophysiologic changes in renal physiology which occur during pregnancy. In the second part, we present common and rare disorders which lead to Pr-AKI and provide an overview of the available treatment options.

Acute kidney injuries induced by thrombotic microangiopathy following severe hemorrhage in puerperants: a case series and literature review

BACKGROUND

Acute kidney injury in puerperants is generally caused by acute tubular necrosis and occasionally by thrombotic microangiopathy (TMA) following post-partum hemorrhage. However, TMA leads to worse clinical outcomes and is rarely reported in the literature. Therefore, this study aimed to evaluate the pathological mechanism behind the development of TMA in puerperants to improve the diagnosis and treatment of this condition.

METHODS

Three patients diagnosed with severe postpartum hemorrhage and TMA from 2014 to 2017 at a nephrology center were retrospectively investigated.

RESULTS

All patients had severe hemorrhage during delivery with a mean blood loss, 4.0 L (range, 2.7-5.0 L). AKI developed rapidly in these patients and was treated with hemodialysis. Following treatment, the mean volume of packed red blood cells was 2.3 L (range, 1.2-3.6 L), and the mean volume of resuscitation fluid was 3.7 L (range, 3.5-4.0 L). All patients had renal biopsy specimens with typical TMA and ATN changes on light microscopy. Two patients required a hysterectomy while another two patients received respiratory support. Only one patient received plasma exchange. None of the patients had recovered normal kidney function by the final follow-up (26-61 months), with two patients having stage 3 chronic kidney disease, and one patient having an end-stage renal disease requiring maintenance hemodialysis.

CONCLUSION

Severe postpartum hemorrhage could lead to TMA, in addition to the common finding of ATN. Renal histology revealed that poor renal outcomes could be attributed to TMA coexisting with ATN. The potential mechanism was ischemia-reperfusion, which was followed by endothelial cell injury and activation of the alternative complement pathway.

Acute kidney injury e-alerts in pregnancy: rates, recognition and recovery

BACKGROUND

Acute kidney injury (AKI) in pregnancy (Pr-AKI) is associated with substantial maternal morbidity and mortality. E-alerts are routinely used for detection of AKI in non-pregnant patients but their role in maternity care has not been explored.

METHODS

All pregnant or postpartum women with AKI e-alerts for AKI Stages 1-3 (Kidney Disease Improving Global Outcomes (KDIGO) criteria) were identified at a tertiary centre >2 years. Two women matched by delivery date for each case were selected as controls. AKI stage, recognition of AKI, pregnancy outcomes, renal recovery, AKI aetiology and risk factors were extracted from electronic patient records.

RESULTS

288 of 11 922 (2.4%) women had AKI e-alerts, of which only 118 (41%) were recognized by the obstetric team. Common Pr-AKI causes included infection (48%), pre-eclampsia (26%) and haemorrhage (25%), but no cause was identified in 15% of women. Renal function recovered in 213 (74%) women, but in 47 (17%) repeat testing was not undertaken and 28 (10%) did not recover function. Hypertensive disorders of pregnancy and Caesarean section were associated with increased incidence of Pr-AKI compared with controls.

CONCLUSIONS

Pr-AKI e-alerts were identified in ∼1 in 40 pregnancies. However, a cause for Pr-AKI was not identified in many cases and e-alerts may have been triggered by gestational change in serum creatinine. Pregnancy-specific e-alert algorithms may be required. However, 1 in 10 women with Pr-AKI had not recovered kidney function on repeat testing. Better understanding of long-term impacts of Pr-AKI on pregnancy and renal outcomes is needed to inform relevant Pr-AKI e-alert thresholds.

Clinical characteristics and prognosis of postpartum acute kidney injury

Objective

To investigate the clinical characteristics and prognoses of patients with postpartum acute kidney injury (PPAKI).

Methods

We retrospectively reviewed the clinical presentations, laboratory examinations, treatments, and outcomes of patients with PPAKI admitted to our hospital from January 2013 to December 2017. We then analyzed the clinical characteristics and prognoses of the mothers and their infants.

Results

Of 37 patients diagnosed with PPAKI, 26 (70.3%) received treatment in the intensive care unit, mainly for hemolysis, elevated liver enzymes, low platelet count (HELLP) syndrome (28/37, 75.7%), pre-eclampsia (26/37, 70.3%), and postpartum hemorrhage (22/37, 59.5%). Twenty patients required renal replacement treatment (RRT), but renal recovery times were similar in the RRT and non-RRT groups. Renal function recovered completely in 30 patients (81.1%) and partially in one patient (2.7%), and was not re-examined in two patients (5.4%). Three patients (8.1%) were lost to follow-up. Only one patient (2.7%) remained dialysis-dependent, and no maternal deaths occurred. The preterm birth, low birth weight, and infant survival rates were 70.7% (29/41), 68.3% (28/41), and 78.0% (32/41), respectively.

Conclusion

RRT does not reduce renal recovery time compared with non-RRT. Overall, the prognoses of both mothers and their fetuses are good following treatment for PPAKI.

Association of D-dimers with acute kidney injury in pregnant women: a retrospective study

Objective

This study was performed to determine the association of D-dimers measured at the time of admission with the development of acute kidney injury (AKI) in pregnant women.

Methods

We retrospectively analyzed the data of 625 women who developed AKI and 628 normal pregnant women admitted to our hospital from January 2014 to December 2018. The primary endpoint of the study was the development of AKI in pregnant women, and the secondary endpoint was the development of dialysis and death in women with AKI. Univariate and multivariate analyses were conducted.

Results

The D-dimer concentration was significantly higher in patients with than without pregnancy-related AKI (PR-AKI). Multivariate logistic regression showed that a D-dimer concentration of >1108 ng/mL was an independent predictor of PR-AKI. The area under the curve of the D-dimer concentration as a prognostic indicator of PR-AKI was 0.652 (95% confidence interval, 0.622–0.683), that for patients with PR-AKI undergoing dialysis was 0.819 (95% confidence interval, 0.709–0.928), and that for patients who died was 0.828 (95% confidence interval, 0.670–0.986).

Conclusion

The D-dimer concentration is significantly associated with the development of AKI in pregnant patients and may increase the risk of dialysis and death in women with AKI.

Factors associated with acute kidney injury during delivery or the postpartum period: A case control study

INTRODUCTION

To investigate the incidence of risk factors associated with acute kidney injury(AKI) occurring during the intrapartum or the immediate postpartum period.

MATERIAL AND METHODS

A retrospective case control study in a tertiary UK hospital of pregnant women identified with AKI in labour or in the postpartum period between July 2019 and June 2020 was carried out. Women identified with pregnancy related AKI (pr-AKI) in labour or postpartum were compared with a matched cohort of women with no evidence of pr-AKI, using multiple regression analysis.

RESULTS

In 4600 births, 71 women with pr-AKI and 142 control women were identified. The antenatal and intrapartum risk factors strongly associated with pr-AKI were pre-eclampsia, prolonged ruptured membranes, delivery by emergency caesarean section and greater blood loss at delivery (all p < 0.001 in multivariable regression).

CONCLUSION

Pr-AKI is relatively common, occurring in 1.5 % of our cohort. Women who are overweight, have prolonged rupture of the membranes, an emergency caesarean section and/or a postpartum haemorrhage are at greatest risk. Clinicians should be check renal function before prescribing non-steroidal medication for postpartum pain relief if there are risk factors for AKI.

Renal and cardiovascular repercussions in preeclampsia and their impact on fluid management: a literature review

Preeclampsia is a multifactorial condition associated with significant morbidity and mortality. Fluid therapy in these patients is challenging since volume expansion may precipitate pulmonary edema, and fluid restriction may worsen renal function. Furthermore, cardiac impairment may introduce an additional component to the hemodynamic management. This article reviews the repercussions of preeclampsia on renal and cardiovascular systems and the development of pulmonary edema, as well as to discuss fluid management, focusing on the mitigation of adverse outcomes and monitoring alternatives. The literature review was carried out using PubMed, Embase, and Google Scholar databases from May 2019 to March 2020. Papers addressing the subjects of interest were included regardless of the publication language. There is a current trend towards restricting the administration of fluids in women with non-complicated preeclampsia. However, patients with preeclampsia may experience hemorrhagic shock, requiring volume resuscitation. In this case, hemodynamic monitoring is recommended to guide fluid therapy while avoiding complications.

Preeclampsia, HELLP Syndrome, and Postpartum Renal Failure with Thin Basement Membrane Nephropathy: Case Report and a Brief Review of Postpartum Renal Failure

A 36-year-old primigravida female from a birthing center was referred for elevated blood pressure to the hospital two days after normal spontaneous vaginal delivery with nausea, vomiting, and diarrhea. During this two-day period, she was experiencing persistent vaginal bleeding and lower abdominal pains for which she took six doses of 600 mg ibuprofen. Further laboratory evaluation reflected leukocytosis, anemia, thrombocytopenia, elevation of liver enzymes, and renal failure with hyperkalemia requiring emergent hemodialysis once in the Medical Intensive Care Unit (MICU). She was diagnosed with HELLP syndrome with underlying preeclampsia. A week later, due to hypertension controlled with medications and nonoliguric renal failure with no active urine sediments, a renal biopsy was indicated to direct management. The renal biopsy supported the diagnosis of diffuse severe acute tubulointerstitial nephritis with hypereosinophilia and thin basement membrane nephropathy (see figures). She was subsequently treated with high-dose steroids which resulted in the normalization of blood pressures and renal function returning to baseline. We report the first case of acute tubulointerstitial nephritis in an individual with thin basement membrane nephropathy secondary to postpartum complications.

Acute Kidney Injury in Pregnancy

Acute kidney injury in pregnancy is a public health problem and a significant cause of maternal and fetal morbidity and mortality. The incidence of pregnancy-related acute kidney injury has increased in the developed countries, theorized to be the result of an increase in pregnancies in advanced maternal age, and continues to remain higher in developing countries owing to inadequate antenatal care. While hyperemesis gravidarum is a common cause of pregnancy-related acute kidney injury during the first trimester, complications such as preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, acute fatty liver disease of pregnancy, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome are important causes of acute kidney injury later in the pregnancy. Diagnosis of pregnancy-related acute kidney injury can be difficult owing to lack of diagnostic criteria and overlapping clinical features between various causes. General measures to treat pregnancy-related acute kidney injury include identification of the underlying cause of kidney injury, intravenous fluid resuscitation, timely initiation of dialysis if needed, and prompt fetal delivery, if necessary. Specific treatment includes steroid and immunosuppressive therapy for glomerulonephritis; prompt delivery for severe preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, and acute fatty liver of pregnancy; and plasmapheresis and eculizumab for thrombotic microangiopathies such as thrombotic thrombocytopenic purpura and atypical hemolytic uremic syndrome.

Extracellular vesicles: a novel window into kidney function and disease

PURPOSE OF REVIEW

There has been an increasing interest in extracellular vesicles as potential diagnostic, prognostic or therapeutic biomarkers for various kidney diseases, as extracellular vesicles mediate cell-cell or intercellular communication. This review explores the current state of knowledge regarding extracellular vesicles as a tool for examining kidney physiology and disease.

RECENT FINDINGS

Urinary extracellular vesicles may be useful as biomarkers to detect abnormal function in renal endothelial and tubular cells as well as podocytes. Recent studies suggest that urinary extracellular vesicles may facilitate early diagnosis and/or monitoring in acute kidney injury, glomerular disease, autosomal dominanat polycyst kidney disease and urinary tract malignancies. Circulating extracellular vesicles may serve as biomarkers to assess cardiovascular disease.

SUMMARY

Urinary and circulating extracellular vesicles have gained significant interest as potential biomarkers of renal diseases. Analysis of extracellular vesicles may serve as a logical diagnostic approach for nephrologists as well as provide information about disease pathophysiology.

Acute kidney injury in pregnancy

PURPOSE OF REVIEW

Pregnancy-related acute kidney injury (Pr-AKI) is associated with increased maternal and fetal morbidity and mortality and remains a large public health problem.

RECENT FINDINGS

Pr-AKI incidence has globally decreased over time for the most part. However, the cause presents a disparity between developing and developed countries, reflecting differences in socioeconomic factors and healthcare infrastructure - with the noteworthy outlier of increased incidence in the United States and Canada. Although Pr-AKI can be secondary to conditions affecting the general population, in most cases it is pregnancy specific. Septic abortion, hyperemesis gravidarum, and hemorrhage have become less prevalent with access to healthcare but are being displaced by thrombotic microangiopathies, such as preeclampsia, hemolysis, elevated liver enzymes, low platelets syndrome, thrombotic thrombocytopenic purpura, and pregnancy-associated hemolytic-uremic syndromes, as well as acute fatty liver of pregnancy. Understanding these conditions plays a pivotal role in the timely diagnosis and enhancement of therapeutic approaches.

SUMMARY

In this review, we focus on the renal physiology of the pregnancy, epidemiology, and specific conditions known to cause Pr-AKI, summarizing diagnostic definition, insights in pathophysiology, clinical considerations, and novel treatment approaches, thus providing the reader a framework of clinically relevant information for interdisciplinary management.

Pregnancy-Related Acute Kidney Injury in the United States: Clinical Outcomes and Health Care Utilization

BACKGROUND

Acute kidney injury (AKI) during pregnancy is a public health problem and is associated with maternal and fetal morbidity and mortality. Clinical outcomes and health care utilization in pregnancy-related AKI, especially in women with diabetes, are not well studied.

METHODS

Using data from the 2006 to 2015 Nationwide Inpatient Sample, we identified 42,190,790 pregnancy-related hospitalizations in women aged 15-49 years. We determined factors associated with AKI, including race/ethnicity, and associations between AKI and inpatient mortality, and between AKI and cardiovascular (CV) events, during pregnancy-related hospitalizations. We calculated health care expenditures from pregnancy-related AKI hospitalizations.

RESULTS

Overall, the rate of AKI during pregnancy-related hospitalizations was 0.08%. In the adjusted regression analysis, a higher likelihood of AKI during pregnancy-related hospitalizations was seen in 2015 (OR 2.20; 95% CI 1.89-2.55) than in 2006; in older women aged 36-40 years (OR 1.49; 95% CI 1.36-1.64) and 41-49 years (OR 2.12; 95% CI 1.84-2.45) than in women aged 20-25 years; in blacks (OR 1.52; 95% CI 1.40-1.65) and Native Americans (OR 1.45; 95% CI 1.10-1.91) than in whites, and in diabetic women (OR 4.43; 95% CI 4.04-4.86) than in those without diabetes. Pregnancy-related hospitalizations with AKI were associated with a higher likelihood of inpatient mortality (OR 13.50; 95% CI 10.47-17.42) and CV events (OR 9.74; 95% CI 9.08-10.46) than were hospitalizations with no AKI. The median cost was higher for a delivery hospitalization with AKI than without AKI (USD 18,072 vs. 4,447).

CONCLUSION

The rates of pregnancy-related AKI hospitalizations have increased during the last decade. Factors associated with a higher likelihood of AKI during pregnancy included older age, black and Native American race/ethnicity, and diabetes. Hospitalizations with pregnancy-related AKI have an increased risk of inpatient mortality and CV events, and a higher health care utilization than do those without AKI.

Acute kidney injury associated with preeclampsia or hemolysis, elevated liver enzymes, and low platelets syndrome

OBJECTIVE

To determine the prevalence of acute kidney injury (AKI), placental abruption and postpartum hemorrhage in patients with preeclampsia or HELLP syndrome.

STUDY DESIGN

A retrospective study of patients with preeclampsia or HELLP syndrome treated at the University of Mississippi Medical Center from January 2000 through December 2010.

MAIN OUTCOME MEASURES

Relationships among the obstetric complications of placental abruption, postpartum hemorrhage, and AKI (serum creatinine >107 µmol/L) of women with preeclampsia or HELLP syndrome. Additional analysis was undertaken to explore if there was a correlation between postpartum hemorrhage/placental abruption and the severity of HELLP syndrome according to the Mississippi classification system.

RESULTS

Data from 1276 women over 11 years were included in the analysis. 67 of 466 patients (14.4%) with HELLP syndrome and 38 of 810 preeclampsia patients (4.7%) met criteria for AKI. Women with either placental abruption or postpartum hemorrhage had statistically significant increased odds of also having AKI (p < 0.01). Women with HELLP and AKI were also more likely to experience either placental abruption or postpartum hemorrhage. Women with Class 1 HELLP with placental abruption or postpartum hemorrhage were also more likely to have AKI than women with preeclampsia.

CONCLUSION

HELLP syndrome, AKI and placental abruption or postpartum hemorrhage appear to be interrelated. AKI occurs more frequently in women with HELLP syndrome with or without associated postpartum hemorrhage and placental abruption.

Role of plasma exchange in postpartum microangiopathies: An experience from a tertiary care center

BACKGROUND:

Postpartum microangiopathies are rare but are associated with high maternal and fetal mortality requiring early diagnosis and prompt treatment to improve the outcome.

AIMS AND OBJECTIVES:

This retrospective study aims to assess the efficacy of plasma exchange (PE) therapy in postpartum thrombotic microangiopathies.

MATERIALS AND METHODS:

We did retrospective analysis of all plasma exchange procedures performed in patients of postpartum thrombotic microangiopathies over a period of 1 year (2015-2016). Patient's pre- and post-plasma exchange hematological and biochemical parameters were recorded and compared for analyzing the response to the therapy. Patients were followed telephonically even after their discharge from the hospital.

RESULTS:

Hematological and renal profile improved in 8 out of 9 patients after PE therapy. Survival after PE therapy was 40% in post partum atypical HUS and 75% in patients with HELLP syndrome at 4 months of follow up.

CONCLUSION:

Early initiation of PE therapy in postpartum thrombotic microangiopathies can reduce morbidity and mortality associated with them.

The Changing Landscape of Acute Kidney Injury in Pregnancy from an Obstetrics Perspective

Pregnancy-related acute kidney injury (PR-AKI) is a heterogeneous disorder with multiple aetiologies that can occur at any time throughout pregnancy and the post-partum period. PR-AKI is an important obstetric complication that is associated with significant maternal and foetal morbidity and mortality. Although there has been an overall decline in the incidence of PR-AKI worldwide, a recent shift in the occurrence of this disease has been reported. Following improvements in obstetric care, PR-AKI incidence has been reduced in developing countries, whereas an increase in PR-AKI incidence has been reported in developed countries. Awareness of the physiological adaptations of the renal system is essential for the diagnosis and management of kidney impairment in pregnancy. In this review we scrutinize the factors that have contributed to the changing epidemiology of PR-AKI and discuss challenges in the diagnosis and management of acute kidney injury (AKI) in pregnancy from an obstetrics perspective. Thereafter we provide brief discussions on the diagnostic approach of certain PR-AKI aetiologies and summarize key therapeutic measures.

Integration of suboptimal health status evaluation as a criterion for prediction of preeclampsia is strongly recommended for healthcare management in pregnancy: a prospective cohort study in a Ghanaian population

Background

Normotensive pregnancy may develop into preeclampsia (PE) and other adverse pregnancy complications (APCs), for which the causes are still unknown. Suboptimal health status (SHS), a physical state between health and disease, might contribute to the development and progression of PE. By integration of a routine health measure in this Ghanaian Suboptimal Health Cohort Study, we explored the usefulness of a 25-question item SHS questionnaire (SHSQ-25) for early screening and prediction of normotensive pregnant women (NTN-PW) likely to develop PE.

Methods

We assessed the overall health status among a cohort of 593 NTN-PW at baseline (10-20 weeks gestation) and followed them at 21-31 weeks until 32-42 weeks. After an average of 20 weeks follow-up, 498 participants returned and were included in the final analysis. Hematobiochemical, clinical and sociodemographic data were obtained.

Results

Of the 498 participants, 49.8% (248/498) had 'high SHS' at baseline (61.7% (153/248) later developed PE) and 38.3% (95/248) were NTN-PW, whereas 50.2% (250/498) had 'optimal health' (17.6% (44/250) later developed PE) and 82.4% (206/250) were NTN-PW. At baseline, high SHS score yielded a significantly (p < 0.05) increased adjusted odds ratio, a wider area under the curve (AUC) and a higher sensitivity and specificity for the prediction of PE (3.67; 0.898; 91.9% and 87.8%), PE coexisting with intrauterine growth restriction (2.86, 0.838; 91.5% and 75.9%), stillbirth (2.52; 0.783; 96.6% and 60.0%), hemolysis elevated liver enzymes and low platelet count (HELLP) syndrome (2.08; 0.800; 97.2% and 63.8%), acute kidney injury (2.20; 0.825; 95.3% and 70.0%) and dyslipidaemia (2.80; 0.8205; 95.7% and 68.4%) at 32-42 weeks gestation.

Conclusions

High SHS score is associated with increased incidence of PE; hence, SHSQ-25 can be used independently as a risk stratification tool for adverse pregnancy outcomes thereby creating an opportunity for predictive, preventive and personalized medicine.

Renal disease in pregnancy: Fetal, neonatal and long-term outcomes

Renal disease in women of childbearing age is estimated to be approximately 3%; consequently, renal disease is not an uncommon comorbidity in pregnancy. There has been considerable evidence published over the last 20 years to suggest that renal disease in pregnancy is associated with higher maternal, fetal, and offspring morbidity. Studies published are largely heterogeneous; include unmatched cohort studies; and focus on early neonatal outcomes such as prematurity, small for gestational age, and neonatal unit admission. There appears to be an inverse relationship between maternal renal function and likelihood of neonatal morbidity using these outcome measures. Overall though, data regarding medium-to long-term outcomes for children born to mothers with renal disease are scarce. However, in view of emerging epidemiological evidence regarding cardiovascular programming in intrauterine life in those born premature or small for gestational age, it is likely that this population of children remain at high risk of cardiovascular disease as adults. The scope of this review is to amalgamate and summarize existing evidence regarding the outcomes of infants born to mothers with renal disease. Focus will be given to pregnancy-related acute kidney injury, chronic kidney disease, dialysis, and transplantation.

Acute Kidney Injury in Pregnancy: The Need for Higher Awareness. A Pragmatic Review Focused on What Could Be Improved in the Prevention and Care of Pregnancy-Related AKI, in the Year Dedicated to Women and Kidney Diseases

Pregnancy-related acute kidney injury (pAKI), preeclampsia (PE), and the hypertensive disorders of pregnancy are closely related conditions, which are, in turn, frequently linked to pre-existing and often non-diagnosed chronic kidney disease (CKD). The current literature and research mainly underline the effects of pregnancy complications on the offspring; this review strongly emphasizes the maternal health as well. These conditions not only negatively affect pregnancy outcomes, but have a relevant effect on the future health of affected mothers and their children. Therefore, dedicated diagnostic and follow-up programs are needed, for optimizing materno-foetal health and reducing the impact of pregnancy-related problems in the mothers and in the new generations. This narrative review, performed on the occasion of the 2018 World Kidney Day dedicated to women’s health, focuses on three aspects of the problem. Firstly, the risk of AKI in the hypertensive disorders of pregnancy (the risk is the highest in developing countries; however PE is the main cause of pregnancy related AKI worldwide). Secondly, the effect of AKI and the hypertensive disorders of pregnancy on the development of CKD in the mother and offspring: long-term risks are increased; the entity and the trajectories are still unknown. Thirdly, the role of CKD in the pathogenesis of AKI and the hypertensive disorders of pregnancy: CKD is a major risk factor and the most important element in the differential diagnosis; pregnancy is a precious occasion for early diagnosis of CKD. Higher awareness on the importance of AKI in pregnancy is needed to improve short and long term outcomes in mothers and children.

Pregnancy protects the kidney from acute ischemic injury

A complex analysis of acute kidney injury (AKI) in pregnant women shows that it is caused by the interaction of gestation-associated pathologies and beneficial signaling pathways activated by pregnancy. Studies report an increase in the regeneration of some organs during pregnancy. However, the kidney response to the injury during pregnancy has not been addressed. We investigated the mechanisms of the pregnancy influence on AKI. During pregnancy, the kidneys were shown to be more tolerant to AKI. Pregnant animals showed remarkable preservation of kidney functions after ischemia/reperfusion (I/R) indicated by the decrease of serum creatinine levels. The pregnant rats also demonstrated a significant decrease in kidney injury markers and an increase in protective markers. Two months after the I/R, group of pregnant animals had a decreased level of fibrosis in the kidney tissue. These effects are likely linked to increased cell proliferation after injury: using real-time cell proliferation monitoring we demonstrated that after ischemic injury, cells isolated from pregnant animal kidneys had higher proliferation potential vs. control animals; it was also supported by an increase of proliferation marker PCNA levels in kidneys of pregnant animals. We suggest that these effects are associated with hormonal changes in the maternal organism, since hormonal pseudopregnancy simulated effects of pregnancy.