The influence of antecedent renal disease on pregnancy

Glomerular diseases in pregnancy: pragmatic recommendations for clinical management

Our understanding of the various aspects of pregnancy in women with kidney diseases has significantly improved in the last decades. Nevertheless, little is known about specific kidney diseases. Glomerular diseases are not only a frequent cause of chronic kidney disease in young women, but combine many challenges in pregnancy: immunologic diseases, hypertension, proteinuria, and kidney tissue damage. An international working group undertook the review of available current literature and elicited expert opinions on glomerular diseases in pregnancy with the aim to provide pragmatic information for nephrologists according to the present state-of-the-art knowledge. This work also highlights areas of clinical uncertainty and emphasizes the need for further collaborative studies to improve maternal and fetal health.

Pregnancy in Women With Preexisting Glomerular Diseases: A Single-Center Experience

Aim

Women with glomerular diseases are often of childbearing age. Besides lupus nephritis, data regarding pregnancy in patients with glomerular diseases are limited, posing a challenging task to attending nephrologists. This study aimed to investigate the pregnancy outcomes and the impact on the underlying glomerular disease among women followed in our institution.

Methods

A single-center retrospective cohort study of women with biopsy-proven glomerular diseases who experienced pregnancy between 2010 and 2020. We analyzed data before, during, and after gestation.

Results

A total of 22 women, 13 women with primary and 9 women with secondary glomerular diseases, were included in this study. Most patients (82%) had received immunosuppressive treatment at various times before pregnancy. All the women were in remission, either complete (62%) or partial (38%), with well-preserved renal function (82%) before conception. A total of 30 live births and 1 stillbirth were recorded; the rate of preterm delivery was 23%. Renal function and proteinuria remained stable during pregnancy. Preeclampsia was observed in 6.7% of patients and disease relapse in 6.9% of the pregnancies.

Conclusion

Pregnancy was associated with a low frequency of adverse events in women with underlying glomerular diseases, provided they have quiescent disease and preserved renal function.

Maternal and Fetal Outcomes of Pregnancy in Nephrotic Syndrome Due to Primary Glomerulonephritis

Chronic kidney disease (CKD) affects 3% of pregnancies, impacting on maternal and fetal outcomes, and at the same time, a recurrent question in nephrology regards gestation impact on kidney function. Observational studies stated that CKD stage, pre-existent hypertension, and proteinuria are the main predictors of possible complications, such as maternal CKD progression, maternal or fetal death, prematurity, small for gestational age (SGA) newborn, or admission to the neonatal intensive care unit. In this regard, given the prominence of proteinuria among other risk factors, we focused on primary nephrotic syndrome in pregnancy, which accounts for 0.028% of cases, and its impact on materno-fetal outcomes and kidney survival. Data extracted from literature are scattered because of the small cohorts investigated in each trial. However, they showed different outcomes for each glomerular disease, with membranous nephropathy (MN) having a better maternal and fetal prognosis than focal and segmental glomerulosclerosis (FSGS), membranoproliferative glomerulonephritis (MPGN), or minimal change disease (MCD). Nephrotic syndrome does not have to discourage women to undertake a pregnancy, but the correct management may include a specific evaluation of risk factors and follow-up for adverse materno-fetal events and/or maternal kidney disease progression.

Glomerular Disease and Pregnancy

Nephrologists are routinely involved in the care of pregnant women with glomerulonephritis. Prepregnancy counseling is vital to inform women of the potential risks of pregnancy and to reduce those risks by optimizing clinical status and medications. In general, for all glomerulonephritides, the best pregnancy outcomes are achieved when the disease is in remission and the woman has preserved renal function with no proteinuria or hypertension. Each glomerulonephritis has specific considerations, for example in lupus nephritis, mycophenolate is teratogenic and must be stopped at least 6 weeks before conception, hydroxychloroquine is recommended for all pregnant women, and flares are frequently encountered and must be treated appropriately. De novo glomerulonephritis should be considered when significant proteinuria is found early in pregnancy or an acute kidney injury with active urine is encountered. Biopsy can be safely undertaken in the first trimester. Treatment is often with corticosteroids, azathioprine, and/or tacrolimus. Rituximab is increasingly used for severe disease. Women with glomerulonephritis should ideally be managed in a joint renal-obstetric clinic. This review details the approach to the care of women with glomerulonephritis from prepregnancy counseling, through antenatal care and delivery, to the postpartum period. Special attention is given to medications and treatment of glomerulonephritis in pregnancy.

Case study of tacrolimus as an effective treatment for idiopathic membranous glomerulonephritis in pregnancy

BACKGROUND

Tacrolimus has been used in pregnant women following transplantation and for management of lupus nephritis. We report a case of successful control of nephrotic syndrome due to membranous glomerulonephritis during pregnancy using tacrolimus.

CASE REPORT

A 26-year-old female presented with severe nephrotic syndrome in her first pregnancy. Post-partum renal biopsy confirmed idiopathic membranous glomerulonephritis. She had persistent proteinuria of 6 g/day with hypoalbuminaemia despite angiotensin receptor blockade. Treatment with tacrolimus monotherapy led to remission of proteinuria, three months prior to conceiving again. She maintained remission with tacrolimus therapy in pregnancy, resulting in a successful birth outcome.

CONCLUSIONS

Membranous glomerulonephritis can be successfully and safely managed with tacrolimus monotherapy during pregnancy. This provides an alternative immunosuppressant with a favourable side effect profile suitable for use in women planning a pregnancy when other immunosuppressive drugs should be avoided.

Chronic Kidney Disease and Pregnancy

Women with chronic kidney disease (CKD) are at risk for adverse pregnancy-associated outcomes, including progression of their underlying renal dysfunction, a flare of their kidney disease, and adverse pregnancy complications such as preeclampsia and preterm delivery. Earlier-stage CKD, as a rule, is a safer time to have a pregnancy, but even women with end-stage kidney disease have attempted pregnancy in recent years. As such, nephrologists need to be comfortable with pregnancy preparation and management at all stages of CKD. In this article, we review the renal physiologic response to pregnancy and the literature with respect to both expected maternal and fetal outcomes among young women at various stages of CKD, including those who attempt to conceive while on dialysis. The general management of young women with CKD and associated complications, including hypertension and proteinuria are discussed. Finally, the emotional impact these pregnancies may have on young women with a chronic disease and the potential benefits of care in a multidisciplinary environment are highlighted.

Pregnancy and Glomerular Disease: A Systematic Review of the Literature with Management Guidelines

During pregnancy, CKD increases both maternal and fetal risk. Adverse maternal outcomes include progression of underlying renal dysfunction, worsening of urine protein, and hypertension, whereas adverse fetal outcomes include fetal loss, intrauterine growth restriction, and preterm delivery. As such, pregnancy in young women with CKD is anxiety provoking for both the patient and the clinician providing care, and because the heterogeneous group of glomerular diseases often affects young women, this is an area of heightened concern. In this invited review, we discuss pregnancy outcomes in young women with glomerular diseases. We have performed a systematic review in attempt to better understand these outcomes among young women with primary GN, we review the studies of pregnancy outcomes in lupus nephritis, and finally, we provide a potential construct for management. Although it is safe to say that the vast majority of young women with glomerular disease will have a live birth, the counseling that we can provide with respect to individualized risk remains imprecise in primary GN because the existing literature is extremely dated, and all management principles are extrapolated primarily from studies in lupus nephritis and diabetes. As such, the study of pregnancy outcomes and management strategies in these rare diseases requires a renewed interest and a dedicated collaborative effort.

Pregnancy Outcomes in Patients with Glomerular Disease Attending a Single Academic Center in North Carolina

BACKGROUND

Contemporary data regarding pregnancy outcomes in US patients with primary glomerular diseases are lacking. We aimed to report fetal and maternal outcomes among women with biopsy-proven primary glomerular disease who received obstetric care at a single large academic US center.

METHODS

All women with a biopsy-confirmed primary glomerular disease diagnosis and without end-stage kidney disease who received obstetric care at the University of North Carolina (UNC) Hospitals (1996-2015) were identified using the Glomerular Disease Collaborative Network registry and the UNC Hospitals Perinatal Database. The primary study outcome was perinatal death (stillbirth at >20 weeks or neonatal death). Secondary outcomes included premature birth (<37 weeks), birth weight, preeclampsia, and kidney function changes (postpartum vs. baseline). Demographics, clinical characteristics, and outcomes were compared across glomerular disease subtypes.

RESULTS

Among 48 pregnancies in 43 women (IgA nephropathy n = 17, focal segmental glomerulosclerosis [FSGS] n = 16, membranous nephropathy n = 6, minimal change disease n = 4), 13% of pregnancies resulted in perinatal death and 48% of babies were born prematurely. From a maternal perspective, 33% of pregnancies were complicated by preeclampsia, 39% by a doubling of urinary protein, and 27% by a ≥50% increase in serum creatinine. Outcome differences across glomerular disease subtypes were not statistically significant, although decline in kidney function appeared most frequent in FSGS.

CONCLUSION

Adverse pregnancy outcomes are frequently observed in women with glomerular disease. The independent influence of glomerular disease subtype on outcomes requires further study. More widespread reporting and analysis of pregnancy outcomes in women with glomerular disease are urgently needed.

Pregnancy with chronic kidney disease: maternal and fetal outcome

OBJECTIVE

Pregnancy with chronic kidney disease (CKD) is considered to be high risk. The purpose of this study was to assess the effect of pregnancy on CKD and the fetomaternal outcome in these patients.

STUDY DESIGN

A retrospective observational study was conducted in the Department of Obstetrics and Gynaecology, All India Institute of medical sciences, New Delhi over a period of 11 years. A total number of 80 pregnant patients with CKD were reviewed. Staging of CKD was done according to glomerular filtration rate (GFR). Maternal demographic profile, stage of CKD, biochemical profile, antenatal and neonatal records were analyzed. The course of pregnancy was then reviewed and note was made of any maternal or fetal complication. At the time of analysis, patients were divided into early (Stage 1, 2) and late stage (Stage 3-5) disease. All the variables were compared between two groups. Data analysis was carried out using SPSS software version 20.0.

RESULTS

There was significantly increased incidence of preeclampsia (p=0.001) and moderate to severe anemia (p=0.001) in late stage disease as compared to early stage. The renal parameters including mean GFR and serum creatinine deteriorated with pregnancy in both the groups. Among fetal complications, the patients in late stage had significantly increased incidence of small for gestational age, low 5min Apgar score and increased NICU admissions. The overall preterm delivery rate was 57.5%. There was an overall increase in the incidence of caesarean section (CS) rate (64%).

CONCLUSIONS

Despite advances in antenatal care, incidence of adverse events in mother and fetus remain high in these women of CKD as compared to the rates expected in the general population. In all patients of CKD planning for pregnancy, the pre-existing disease should be optimized before conception.

Pregnancy across the spectrum of chronic kidney disease

Management of the pregnant woman with chronic kidney disease is difficult for both nephrologists and obstetricians. Prepregnancy counselling with respect to risk stratification, optimization of maternal health prior to pregnancy, as well as management of the many potential pregnancy-associated complications in this complex patient population remains challenging due to the paucity of large, well-designed clinical studies. Furthermore, the heterogeneity of disease and the relative infrequency of pregnancy, particularly in more advanced stages of chronic kidney disease, leaves many clinicians feeling ill prepared to manage these pregnancies. As such, counselling is imprecise and management varies substantially across centers. All pregnancies in women with chronic kidney disease can benefit from a collaborative multidisciplinary approach with a team that consists of nephrologists experienced in the management of kidney disease in pregnancy, maternal-fetal medicine specialists, high-risk pregnancy nursing staff, dieticians, and pharmacists. Further access to skilled neonatologists and neonatal intensive care unit support is essential given the risks for preterm delivery in this patient population. The goal of this paper is to highlight some of the data that currently exist in the literature, provide management strategies for the practicing nephrologist at all stages of chronic kidney disease, and explore some of the knowledge gaps where future multinational collaborative research efforts should concentrate to improve pregnancy outcomes in women with kidney disease across the globe.

Management of Membranous Glomerulonephritis in Pregnancy: A Multidisciplinary Challenge

We present a case of 28-year-old female, who had a past obstetrical history complicated by uncontrolled blood pressure, early onset preeclampsia, and a fetal demise at 29 weeks. Her blood pressure normalized after each pregnancy, and no diagnosis of renal disease was ever established. In her most recent pregnancy, she remained normotensive and initially presented with normal blood urea nitrogen and creatinine levels. However, after the early first trimester, she developed nephrotic range proteinuria, hypoalbuminemia, and peripheral edema. After delivery of the baby, all clinical symptoms rapidly resolved and laboratory values normalized. We review the clinical course, diagnosis, and management of new onset nephrotic syndrome in pregnancy.

Chronic kidney disease in pregnancy

Parturients with renal insufficiency or failure present a significant challenge for the anesthesiologist. Impaired renal function compromises fertility and increases both maternal and fetal morbidity and mortality. Close communication amongst medical specialists, including nephrologists, obstetricians, neonatologists and anesthesiologists is required to ensure the safety of mother and child. Pre-existing diseases should be optimized and close surveillance of maternal and fetal condition is required. Kidney function may deteriorate during pregnancy, necessitating early intervention. The goal is to maintain hemodynamic and physiologic stability while the demands of the pregnancy change. Drugs that may adversely affect the fetus, are nephrotoxic or are dependent on renal elimination should be avoided.

Pregnancy outcome in women with chronic kidney disease: a prospective cohort study

OBJECTIVE

To evaluate pregnancy outcome in women with chronic kidney disease (CKD) or proteinuria in early pregnancy with concomitant risk for preeclampsia (PE).

METHODS

Thirty-six women with CKD (Cr > 100 μmol/L at booking or Cr > 125 μmol/L prepregnancy or proteinuria ≥ 500 mg/24 hours at booking) and 30 women with proteinuria (≥2+) and known clinical risk for PE were enrolled at 14(+0) to 21(+6) weeks. Pregnancy outcomes were assessed.

RESULTS

Women with mild CKD (prepregnancy Cr < 125 µmol/Cr > 100 µmol at booking; n = 22) had high rates of preeclampsia (40%), preterm delivery (<37 weeks' gestation; 54%), SGA infants (<10th adjusted centile; 64%)and perinatal death (5%). Women with moderate/severe CKD (prepregnancy creatinine > 125 µmol; n = 14) had poor perinatal outcomes: preterm delivery (86%) and perinatal death (14%). Women with proteinuria (≥2+) and concomitant risk of PE also had high rates of pre-eclampsia (60%), preterm delivery (40%), and SGA infants (27%).

CONCLUSIONS

Pregnancy complications for women with CKD remain high. Women with risk factors for PE with proteinuria (≥2+) at booking are also high-risk.

Management of renal disease in pregnancy

Although renal disease in pregnancy is uncommon, it poses considerable risk to maternal and fetal health. This article discusses renal physiology and assessment of renal function in pregnancy and the effect of pregnancy on renal disease in patients with diabetes, lupus, chronic glomerulonephritis, polycystic kidney disease, and chronic pyelonephritis. Renal diseases occasionally present for the first time in pregnancy, and diagnoses of glomerulonephritis, acute tubular necrosis, hemolytic uremic syndrome, and acute fatty liver of pregnancy are described. Finally, therapy of end-stage renal disease in pregnancy, dialysis, and renal transplantation are reviewed.

GLOMERULONEPHRITIS AND THE NEPHROTIC SYNDROME IN PREGNANCY

Glomerulonephritis (GN) may be manifest clinically in several ways. It may be asymptomatic and associated with only minor urinary dipstick abnormalities, GN may present with one of the classic renal nephritic or nephrotic syndromes, or may be associated with progressive chronic kidney disease with hypertension and the gradual development of uraemia, or it may present with fulminating life threatening illness with severe acute kidney injury. The development of GN may indicate a primary renal limited disease, or may be secondary in association with systemic diseases such as systemic lupus erythematosus (SLE), myeloma, infections or diabetes. Although immunological abnormalities underlie the development of many forms of GN, precise pathogenic mechanisms remain unclear and diagnostic labels may simply reflect a description of the glomerular histological changes observed (Table 1).

Renal disease in pregnancy

There is an intimate relationship between the kidney and pregnancy. Renal plasma flow increases by 50–70% during a normal pregnancy and the glomerular filtration rate by about 50%.1These changes commence in the first trimester and fall in the last trimester reaching normal levels within about four weeks postpartum. These physiological changes are accompanied by striking anatomical changes which consist of dilatation of the ureter, pelvis and calyces, together with an increase in renal parenchymal size. The dilatation i s more marked on the right and may appear in the first trimester. At term, 90% of pregnant women show this change.2

Antihypertensive therapy during pregnancy

Hypertensive disorders in pregnancy are a leading cause of maternal and perinatal morbidity and mortality. Overall, hypertension complicates approximately 10% of pregnancies. The incidence is higher in patients with predisposing factors including nulliparity, multiple gestation, preexisting hypertension or diabetes, a previous pregnancy complicated by preeclampsia-eclampsia, familial history of preeclampsia, hydrops fetalis and rapidly growing hydatidiform moles.

Outcome of infants born to women with chronic kidney disease

Pregnancy in women with chronic kidney disease is not uncommon and is not without risk to the mother and child. This article reviews the literature on the outcome of infants from pregnancies in women with chronic kidney disease (CKD), including those receiving dialysis and those living with a functional kidney transplant. Pregnancy in women with CKD and end-stage renal disease (ESRD) is associated with a higher rate of premature birth and small-for-gestational-age (SGA) infants, with resultant increase in neonatal mortality. Although congenital anomalies or long-term developmental issues do not appear to be a significant risk, these areas deserve further study, especially as newer immunosuppressive medications are employed in kidney transplant recipients.

Chronic kidney disease and pregnancy: maternal and fetal outcomes

Chronic kidney disease complicates an increasing number of pregnancies, and at least 4% of childbearing-aged women are afflicted by this condition. Although diabetic nephropathy is the most common type of chronic kidney disease found in pregnant women, a variety of other primary and systemic kidney diseases also commonly occur. In the setting of mild maternal primary chronic kidney disease (serum creatinine <1.3 mg/dL) without poorly controlled hypertension, most pregnancies result in live births and maternal kidney function is unaffected. In cases of more moderate and severe maternal primary chronic kidney disease, the incidence of fetal prematurity, low birth weight, and death increase substantially, and the risk of accelerated irreversible decline in maternal kidney function, proteinuria, and hypertensive complications rise dramatically. In addition to kidney function, maternal hypertension and proteinuria portend negative outcomes and are important factors to consider when risk stratifying for fetal and maternal complications. In the setting of diabetic nephropathy and lupus nephropathy, other systemic disease features such as disease activity, the presence of antiphospholipid antibodies, and glycemic control play important roles in determining pregnancy outcomes. Concomitant with advances in obstetrical management and kidney disease treatments, it appears that the historically dismal maternal and fetal outcomes have greatly improved.

Kidney disease is an independent risk factor for adverse fetal and maternal outcomes in pregnancy

BACKGROUND

Kidney disease has long been recognized to adversely affect fetal and maternal outcomes during pregnancy. The goal of this study is to better describe the population of women with kidney disease and provide a contemporary assessment of their risk for adverse events caused by kidney disease after adjustment for other contributing factors.

METHODS

We used Colorado birth and death certificate data for 1989 to 2001. Of 747,368 births during this period, 911 births from women with kidney disease were identified, and 4,606 births from women without kidney disease were randomly selected for comparison. Adverse fetal outcomes included fetal prematurity, low birth weight, or neonatal death, whereas adverse maternal outcomes included preeclampsia, eclampsia, or abruptio placenta.

RESULTS

Women with kidney disease were more likely to have comorbid illnesses, including chronic hypertension, anemia, diabetes, and lung and cardiac disease. Women with kidney disease had a greater frequency of adverse fetal (18.2% versus 9.5%) and maternal outcomes (13.7% versus 4.3%) compared with women without kidney disease (P < 0.0001). The presence of kidney disease independently increased the likelihood of adverse fetal outcomes (adjusted odds ratio [OR], 1.76; 95% confidence interval [CI], 1.40 to 2.21) and occurrence of adverse maternal outcomes, especially in the middle 1990s, among nulliparous women (adjusted OR, 4.07; 95% CI, 2.17 to 7.66).

CONCLUSION

This analysis shows that independent of other risk factors, kidney disease significantly increases the likelihood of unfavorable pregnancy outcomes for both mother and child.

Outcome of pregnancy in women with moderate or severe renal insufficiency

BACKGROUND

Pregnant women with mild preexisting renal disease have relatively few complications of pregnancy, but the risks of maternal and obstetrical complications in women with moderate or severe renal insufficiency remain uncertain.

METHODS

We determined the frequency and types of maternal and obstetrical complications and the outcomes of pregnancy in 67 women with primary renal disease (82 pregnancies). All the women had initial serum creatinine concentrations of at least 1.4 mg per deciliter (124 mumol per liter) and gestations that continued beyond the first trimester.

RESULTS

The mean (+/- SD) serum creatinine concentration increased from 1.9 +/- 0.8 mg per deciliter (168 +/- 71 mumol per liter) in early pregnancy to 2.5 +/- 1.3 mg per deciliter (221 +/- 115 mumol per liter) in the third trimester. The frequency of hypertension rose from 28 percent at base line to 48 percent in the third trimester, and that of high-grade proteinuria (urinary protein excretion, > 3000 mg per liter) from 23 percent to 41 percent. For the 70 pregnancies (57 women) for which data were available during pregnancy and immediately post partum, pregnancy-related loss of maternal renal function occurred in 43 percent. Eight of these pregnancies (10 percent of the total) were associated with rapid acceleration of maternal renal insufficiency. Obstetrical complications included a high rate of preterm delivery (59 percent) and growth retardation (37 percent). The infant survival rate was 93 percent.

CONCLUSIONS

Among pregnant women with moderate or severe renal insufficiency, the rates of complications due to worsening renal function, hypertension, and obstetrical complications are increased, but fetal survival is high.

Influence of pregnancy on the course of primary chronic glomerulonephritis

According to some nephrologists, pregnancy has damaging effects on renal function in primary glomerulonephritis, but the evidence is conflicting. We evaluated the effect of pregnancy on the occurrence of end-stage renal failure (ESRF) in 360 patients with various histological forms of primary glomerulonephritis but with normal renal function (serum creatinine < or = 0.11 mmol/L) at presentation. In actuarial analyses, overall ESRF-free survival did not significantly differ between women who became pregnant after clinical onset of renal disease (n = 171) and those who did not conceive (n = 189). Furthermore, in a case-control study pregnancy did not emerge as a risk factor for progression to ESRF (odds ratio 1.15 [95% CI 0.61-2.18]), whereas the type of glomerulonephritis and hypertension were major determinants. We conclude that pregnancy does not affect the course of renal disease in patients who have normal renal function at conception.

Reflux nephropathy and pregnancy

Reflux nephropathy is one of the renal diseases encountered most frequently in women of childbearing age. Patients with severe bilateral atrophy are the most likely to develop proteinuria, hypertension, focal glomerular sclerosis and progressive chronic renal failure, and those with persistent vesicoureteral reflux are the most likely to suffer recurrent pyelonephritic episodes. Often the disease is clinically latent and first manifests itself in pregnancy, mainly by urinary tract infection but also by proteinuria, hypertension, pre-eclampsia or renal failure. Pregnancy is most often successful and uneventful whenever renal function is normal or near normal and hypertension is absent at conception. Urinary tract infection accounts for frequent morbidity but rarely results in fetal mortality. By contrast, when renal function is significantly impaired, that is in patients whose plasma creatinine concentration is in excess of 0.20-0.22 mmol l-1 at conception, especially when hypertension is also present, there is clearly a high risk of fetal growth retardation or intrauterine death. Moreover, there is a striking risk of rapid worsening of renal function and hypertension, with accelerated progression towards end-stage renal failure. Thus, women with reflux nephropathy should attempt to conceive before the plasma creatinine concentration has reached 0.20 mmol l-1, and patients with values higher than these should be clearly advised of the high risk for both the pregnancy and the progression of the disease.

Gestation in women with kidney disease: prognosis and management

Physicians may be called upon to guide patients with renal disease on the advisability of conceiving or maintaining a gestation, or to manage pregnancies permitted to continue. The prevailing view is that the degree of functional impairment and the presence or absence of hypertension prior to conception determine both pregnancy outcome and the effect of gestation on the natural history of the kidney disorder (Table 3). Normotensive women with minimal dysfunction have a greater than 90% chance of success and there is little evidence that gestation will adversely affect the disease. Presence of hypertension increases the complications rate substantially if not aggressively controlled, and prognosis is also poorer in women with moderate renal dysfunction. Most gestations in the latter group succeed, but at considerable maternal risk: over 20% of these women experience renal functional deterioration, and 30-40% of them have major problems with hypertension. Thus we tend not to recommend pregnancy in patients with moderate renal insufficiency, and definitely discourage gestation when GFR is severely impaired. We advise termination, as most of these gestations fail, and maternal risk is substantial. There are a number of diseases in which pregnancy should not be undertaken, including scleroderma and periarteritis. Some authors believe that women with membranoproliferative glomerulonephritis also do poorly, and opinions differ on the effects of gestation on IgA nephropathy, focal glomerulosclerosis, and reflux nephropathy. Table 4 summarizes our view concerning pregnancy in a number of specific renal disorders. Finally, in addition to the controversies noted above, there are other unresolved problems requiring further study. For instance, protein restriction should be avoided until the effect of this therapeutic manoeuvre on fetal development is evaluated. Also needed are conclusive studies on whether or not the physiological hyperfiltration of human pregnancy affects adversely pre-existing renal disease.

Natural history of chronic proteinuria complicating pregnancy

OBJECTIVE

Although the significance of proteinuria is well-documented for pregnancy complicated by preeclampsia or diabetes, protein excretion of up to 300 mg per day is considered normal for uncomplicated pregnancy. Our purpose was to determine the significance of otherwise "asymptomatic" proteinuria identified during pregnancy.

STUDY DESIGN

We reviewed the perinatal outcome of 65 pregnancies in 53 women with the following criteria: (1) proteinuria exceeding 500 mg per day, (2) no previously known renal disease, (3) no reversible renal dysfunction, and (4) no evidence for preeclampsia at discovery.

RESULTS

Renal insufficiency coexisted in 62% of women, and 40% had chronic hypertension. Excluding 8 abortions, 53 (93%) of 57 pregnancies resulted in live infants; 45% of infants were delivered preterm and 23% had growth retardation. Of these 57 women, 62% demonstrated clinical evidence compatible with superimposed preeclampsia, and although the incidence of preeclampsia was increased with isolated proteinuria (29%), it was increased even more when there was associated chronic hypertension (incidence 100%) or renal insufficiency (incidence 58%). All 21 women who eventually underwent renal biopsy had histologic evidence of renal disease. To date, with only a limited follow-up of these 53 women, 11 (20%) have progressed to end-stage renal disease.

CONCLUSION

"Asymptomatic" proteinuria is associated with a number of adverse pregnancy outcomes and serious long-term maternal morbidity.

Antenatal screening and risk factors for intrauterine growth retardation

Antenatal risk factors in combination with symphysis-fundus distance can identify pregnancies with small infants, who can be divided in genetically small, malformed, and malnourished infants. Only the last category benefit from fetal surveillance. Maternal diseases, pregnancy complications (hypertension), and environmental factors (smoking) are connected to malnourished small infants.

Pregnancy in IgA nephropathy

The impacts of IgA nephropathy and pregnancy on each other were evaluated in 118 women who conceived 168 times between 1970 and 1988. Rates of spontaneous abortion, normal delivery, live birth and perinatal death were 9, 66, 87 and 4%, respectively. Infants born to women with glomerular filtration rates (GFR) lower than 70 ml/min prior to conception had a higher perinatal mortality rate (14% vs. 3%, P less than 0.001). This was also true if pre-pregnancy blood pressures were consistently higher than 140/90 mm Hg (33% vs. 1%, P less than 0.001). These were the figures for the whole 18 year period, but stratification of the data revealed that most adverse results occurred in the 1970's, during which the perinatal death rate was 9%, while it was 0% in the 1980's. Eighty-five women were followed for three years or more. At final follow-up, the rates of decrease in GFR, and increases in blood pressure and proteinuria were 19, 11 and 7%, respectively. In most patients the natural history of IgA nephropathy was similar to that of women who had not experienced pregnancy, but there were five instances where gestation seemed to accelerate functional loss, with rapid development of end-stage or near end-stage renal failure. Most women with IgA nephropathy should anticipate few problems with pregnancy, if they are normotensive and their preconception GFR exceeds 70 ml/min. The gestation in such instances should have little influence on the natural history of their nephropathy.

Specific controversies concerning the natural history of renal disease in pregnancy

Whether or not pregnancy adversely affects the natural course of underlying primary renal disease, and whether fetal outcome is influenced by the type of renal disease per se are controversial issues. We retrospectively analyzed the fetal and maternal outcome in 148 women with various, biopsy-proven histological types of primary chronic glomerulonephritis (GN), including IgA GN (52 patients), membranous GN ([MGN] 20 patients), membranoproliferative type 1 GN ([MPGN] 58 patients), focal and segmental glomerulosclerosis ([FSGS] 13 patients), and minimal change nephrotic syndrome ([MCNS] 22 patients), who were pregnant (with a total of 290 pregnancies) after the clinical onset of GN, and in 104 women with reflux nephropathy (with a total of 254 pregnancies). Fetal outcome was poor in the presence of uncontrolled hypertension, nephrotic range proteinuria, and/or impaired renal function at conception or early in gestation, whatever the type of renal disease. An accelerated, more rapid than expected, worsening of maternal renal function was observed in five GN patients of whom four (two IgA, two MPGN) had serum creatinine (Scr) levels greater than 160 mumol/L (1.8 mg/dL) early in gestation, and in five patients with reflux nephropathy whose Scr at conception ranged from 180 to 490 mumol/L (2.0 to 5.5 mg/dL).(ABSTRACT TRUNCATED AT 250 WORDS)

An overview of pregnancy in women with underlying renal disease

This is a report of a retrospective study of the effects of preexisting glomerular disease and pregnancy on each other. Two hundred forty pregnancies in 166 Japanese women who delivered between 1970 and 1988 were analyzed. There were 206 (86%) live births, 14 (6%) perinatal deaths, and 20 (8%) spontaneous abortions. Perinatal loss was greatest in women with hypertension and/or glomerular filtration rate (GFR) less than 70 mL/min before conception. Pregnancy did not appear to adversely affect the underlying glomerular disease if GFR was greater than 70 mL/min and blood pressure was below 140/90 mm Hg. However, with moderately impaired renal function (creatinine greater than 124 mumol/L [1.4 mg/dL] or GFR less than 50 mL/min), the long-term prognosis was poorer, despite generally favorable obstetrical outcomes. Gravidas with membranoproliferative glomerulonephritis had the highest rates of hypertension (29%) and decreased renal function (33%) at final follow-up, ie, the type and severity of glomerulonephritis had a major impact on clinical course.

Gestation in women with kidney disease: prognosis and management

Physicians may be called upon to guide patients with renal disease on the advisability of conceiving or maintaining a gestation, or to manage pregnancies permitted to continue. The prevailing view is that the degree of functional impairment and the presence or absence of hypertension prior to conception determine both pregnancy outcome and the effect of gestation on the natural history of the kidney disorder (Table 4). Normotensive women with minimal dysfunction have a 90% chance of success and there is little evidence that gestation will adversely affect the disease. Presence of hypertension increases the complications rate substantially, and prognosis is also poorer in women with moderate renal dysfunction. Most gestations in the latter group succeed, but at considerable maternal risk: over 20% of these women experience renal functional deterioration, and 30-40% of them have major problems with hypertension. Thus we tend not to recommend pregnancy in patients with moderate renal insufficiency, and definitely discourage gestation when GFR is severely impaired. There are a number of diseases in which pregnancy should not be undertaken, including scleroderma and periarteritis. Some authors believe that women with membranoproliferative glomerulonephritis also do poorly, and opinions differ on the effects of gestation on IgA nephropathy, focal glomerulosclerosis, and reflux nephropathy. Table 5 summarizes our view concerning pregnancy in a number of specific renal disorders. Finally, in addition to the controversies noted above, there are other unresolved problems requiring further study. For instance, protein restriction should be avoided until the effect of this therapeutic manoeuvre on fetal development is evaluated. Also needed are conclusive studies on whether or not the physiological hyperfiltration of human pregnancy affects adversely pre-existing renal disease.

Reflux nephropathy and pregnancy

Reflux nephropathy is one of the most frequent renal diseases encountered in women of childbearing age. Patients with severe bilateral atrophy are the most likely to develop proteinuria, hypertension, focal glomerular sclerosis and progressive chronic renal failure, and those with persistent vesicoureteral reflux are the most likely to suffer recurrent pyelonephritic episodes. Often the disease is clinically latent and first manifests itself in pregnancy, mainly by urinary tract infection but also by proteinuria, hypertension, pre-eclampsia or renal failure. Pregnancy is most often successful and uneventful whenever renal function is normal or near normal and hypertension is absent at conception. Urinary tract infection accounts for frequent morbidity but rarely results in fetal mortality. By contrast, when renal function is significantly impaired, that is in patients whose plasma creatinine concentration is in excess of 0.18-0.20 mmol/l at conception, especially when hypertension is also present, there is clearly a high risk of severe fetal growth retardation or intrauterine death. Moreover, there is a striking risk of rapid worsening of renal function and hypertension, with accelerated progression towards end-stage renal failure. Thus, women with reflux nephropathy should attempt to conceive before the plasma creatinine concentration has reached 0.18 mmol/l, and patients with values higher than these should be clearly advised of the high risk for both the pregnancy and the progression of the disease.

Renal disease in pregnancy. Three controversial areas: mesangial IgA nephropathy, focal glomerular sclerosis (focal and segmental hyalinosis and sclerosis), and reflux nephropathy

Whether gestation has adverse effects on the course of renal disease is controversial. Three diseases regarding which conflicting opinions are especially noteworthy are IgA nephropathy, focal and segmental hyalinosis and sclerosis, and reflux nephropathy. We analyzed 102 pregnancies in 65 women with IgA nephropathy, noting hypertension in 63% of the gestations (severe in 18%), decreases in renal function in 22%, and biopsy evidence demonstrating a significantly greater amount of glomerular proliferation and crescents as well as focal and segmental hyalinosis and sclerosis when the renal histology from women who were pregnant and those who had never conceived were compared. Our experience with glomerular sclerosis is limited to 28 gestations in 15 patients, but the clinical findings resemble those of women with IgA nephropathy who conceived. Finally, we analyzed 227 pregnancies in 95 women with normal renal function and reflux nephropathy comparing results to 118 gestations in 42 patients with evidence of dysfunction (serum creatinine SCr greater than 1.25 mg/dL). Women with preserved function had good outcomes in general, whereas hypertension (36%) and an accelerated decline in function (8%) were observed in the groups that had moderate renal insufficiency in the initial stage of pregnancy. Increased proteinuria was the best predictor of progression of reflux nephropathy in both groups.