Learning Objectives

By the end of this chapter, learners will be able to:
1. Describe normal physiological changes in renal function during pregnancy and their impact on laboratory interpretation.
2. Recognize how pre-existing kidney disease influences maternal and fetal outcomes and stratify risk pragmatically.
3. Identify common kidney complications in pregnancy, including preeclampsia, AKI, UTI/pyelonephritis, and nephrolithiasis.
4. Apply an evidence-informed diagnostic approach to hypertension, proteinuria, and renal dysfunction in pregnancy.
5. Outline safe, practical management strategies for pregnant patients with kidney disease, including antihypertensives, infection management, dialysis, and post-transplant care.

22.1 Normal Physiological Changes in Renal Function During Pregnancy

Pregnancy induces major renal adaptations to support fetoplacental demands:

• Increased renal plasma flow (RPF) and GFR:
• GFR rises by approximately 30–50% by late first–early second trimester.
• Serum creatinine and urea fall from pre-pregnancy values. In many labs, a creatinine ≥0.9–1.0 mg/dL (≥80–90 micromol/L) in the second or third trimester is higher than expected and should prompt evaluation. Interpret using pregnancy-specific reference ranges when available.

• Creatinine-based eGFR equations are not validated in pregnancy; avoid relying on estimated GFR for decision-making.

• Mild, physiologic proteinuria:

• Protein excretion can increase; values ≥300 mg/day (or spot urine protein/creatinine ratio [uPCR] ≥0.3 g/g) are generally considered abnormal and warrant assessment.

• Glycosuria:

• Increased filtered glucose load may exceed tubular reabsorption; isolated glycosuria can be physiologic but should prompt consideration of gestational diabetes based on glucose testing rather than dipstick alone.

• Collecting system dilatation:

• Hydronephrosis/hydroureter of pregnancy is common, right-sided predominance, from progesterone-mediated smooth muscle relaxation and uterine compression; usually asymptomatic but predisposes to UTI.

• Kidney size:

• Kidneys may lengthen by ~1–1.5 cm.

Practical implications:
– Use trimester-appropriate reference intervals for creatinine and blood pressure.
– A “normal” non-pregnant creatinine can be abnormal in pregnancy.
– Do not diagnose CKD progression based solely on eGFR equations during pregnancy.

22.2 Impact of Pre-existing Kidney Disease on Pregnancy Outcomes

Risk generally correlates with CKD stage, baseline blood pressure, and proteinuria.

• Maternal risks:
• Hypertension or worsening hypertension.
• Preeclampsia (risk increases with higher baseline proteinuria and lower GFR).
• Accelerated loss of kidney function in some, particularly with advanced CKD or active glomerular disease.

• Acute kidney injury (AKI), especially with superimposed preeclampsia or obstetric complications.

• Fetal risks:

• Preterm birth (spontaneous or iatrogenic), intrauterine growth restriction (IUGR), low birth weight.
• Fetal loss/stillbirth with more severe maternal disease.
• Neonatal complications (e.g., respiratory distress); neonatal AKI risk in complicated pregnancies.

Pragmatic risk stratification at conception (typical trends; individualize):
– CKD stages 1–2, well-controlled BP, minimal proteinuria: often favorable outcomes with close monitoring.
– CKD stage ≥3, proteinuria ≥1 g/day, or uncontrolled hypertension: higher risk of preeclampsia, preterm birth, and kidney function decline; counsel accordingly and co-manage with maternal–fetal medicine.

Disease-specific considerations:
– Diabetic kidney disease: higher preeclampsia and preterm risk; optimize glycemia preconception.
– Lupus nephritis: best outcomes when quiescent ≥6 months preconception; avoid conception during active disease.

22.3 Kidney Complications During Pregnancy

1) Preeclampsia
– Definition: New-onset hypertension (≥140/90 mmHg on two occasions at least 4 hours apart) after 20 weeks with either:
– Proteinuria (≥300 mg/24 h or uPCR ≥0.3 g/g), or
– Features of end-organ dysfunction (e.g., thrombocytopenia, elevated liver enzymes, renal insufficiency, pulmonary edema, new cerebral/visual symptoms).
– Severe features include: BP ≥160/110 mmHg, platelets <100,000/µL, creatinine >1.1 mg/dL (97 micromol/L) or doubling of baseline, severe transaminitis, refractory symptoms, or pulmonary edema.
– Pathophysiology: Abnormal placentation and maternal endothelial dysfunction.
– Distinguishing from CKD: Consider rising BP/proteinuria after 20 weeks, falling platelets, transaminitis, and angiogenic biomarkers if available (e.g., sFlt-1/PlGF ratio).
– Management:
– Delivery is definitive; timing individualized by gestational age, severity, and fetal status.
– BP control: labetalol, nifedipine; hydralazine IV for acute severe hypertension. Avoid ACE inhibitors/ARBs and direct renin inhibitors.
– Seizure prophylaxis: magnesium sulfate in preeclampsia with severe features or eclampsia.
– Monitor closely postpartum; disease may present or worsen after delivery.

2) Acute Kidney Injury (AKI) in Pregnancy
– Pregnancy-specific causes:
– Hyperemesis gravidarum (prerenal), preeclampsia/eclampsia/HELLP (glomerular endotheliosis/TMA), acute fatty liver of pregnancy, placental abruption, postpartum hemorrhage/sepsis (ATN), amniotic fluid embolism, pregnancy-triggered aHUS (often postpartum), and TTP.
– Non-pregnancy causes: Sepsis, nephrotoxins (e.g., NSAIDs, contrast when avoidable), obstruction (stones).
– Approach and management:
– Assess volume status, BP, hemolysis labs, LFTs, urine studies, and renal ultrasound.
– Treat precipitating cause; avoid nephrotoxins; judicious fluids; vasopressors if needed.
– Early multidisciplinary care (nephrology, obstetrics, critical care).
– Consider kidney biopsy in selected cases with unclear diagnosis or suspected rapidly progressive GN when benefits outweigh risks, typically in second trimester or postpartum.
– For complement-mediated TMA (aHUS), complement inhibition may be considered with specialist input.

3) Urinary Tract Infections (UTIs) and Pyelonephritis
– Increased susceptibility from urinary stasis and glycosuria.
– Screening: Asymptomatic bacteriuria should be screened early in pregnancy and treated to reduce pyelonephritis risk.
– Treatment: Choose antibiotics with pregnancy-appropriate safety (e.g., beta-lactams, nitrofurantoin except near term in G6PD deficiency; fosfomycin single dose in some settings). Avoid fluoroquinolones and tetracyclines.
– Pyelonephritis: Hospitalize for IV antibiotics, hydration, and monitoring. Consider suppressive prophylaxis after an episode in recurrent cases.

4) Kidney Stones (Nephrolithiasis)
– Presentation overlaps with physiologic hydronephrosis; flank pain, hematuria, infection risk.
– Imaging: Renal/bladder ultrasound first-line; consider MRI urography if needed. Avoid ionizing radiation when possible.
– Management: Analgesia (avoid NSAIDs; acetaminophen preferred; short-course opioids if necessary), hydration. Urgent urologic decompression for obstruction with infection or refractory pain; ureteral stent or nephrostomy as indicated.

22.4 Diagnostic Approach to Kidney Disorders in Pregnant Patients

• Baseline at first prenatal visit (or preconception where possible):
• Blood pressure using appropriate cuff size.
• Urinalysis; culture if bacteriuria suspected or for routine screening early in pregnancy.
• Serum creatinine (use pregnancy reference ranges; avoid eGFR equations).
• Ongoing monitoring:
• Frequency individualized by risk (e.g., every trimester in low-risk; every 2–4 weeks or more in CKD or hypertensive disorders).
• Proteinuria quantification using 24-hour urine protein or spot uPCR/uACR; use the same method longitudinally where feasible.
• Imaging:
• Renal ultrasound for obstruction/hydronephrosis, size, and echogenicity.
• Reserve CT for life-threatening scenarios when other modalities are insufficient; engage radiology/obstetrics to mitigate fetal risk.
• When to consider kidney biopsy:
• Unexplained nephrotic syndrome, rapidly progressive GN, or unclear AKI where results will alter management; second trimester generally has lower procedural risk compared with first and late third.
• Distinguishing superimposed preeclampsia from CKD flare:
• New or sudden rise in BP/proteinuria after 20 weeks, thrombocytopenia, elevated AST/ALT, rising creatinine, symptoms (headache, visual changes).
• Use angiogenic markers (sFlt-1/PlGF) if available to support diagnosis.

22.5 Management Strategies for Pregnant Patients with Kidney Disease

Multidisciplinary management with nephrology, maternal–fetal medicine, anesthesiology, and neonatology is essential.

1) Preconception counseling
– Review maternal and fetal risks; aim for disease remission/stability.
– Optimize BP and proteinuria; update vaccinations; address nutrition and anemia.
– Medication review:
– Stop/avoid teratogens (ACE inhibitors, ARBs, direct renin inhibitors, mycophenolate, cyclophosphamide, methotrexate, and typically spironolactone). Transition to safer alternatives well before conception per local protocols.
– Generally compatible: labetalol, nifedipine, methyldopa; prednisone; azathioprine; calcineurin inhibitors (tacrolimus/cyclosporine). Individualize and monitor drug levels where appropriate.

2) Blood pressure control
– Targets vary by guideline and patient factors; many aim for systolic 120–139 and diastolic 70–89 mmHg unless severe features require urgent control.
– First-line agents: labetalol, long-acting nifedipine. Methyldopa is an option but less favored due to side effects.
– Diuretics may be used cautiously for volume overload; avoid routine initiation for preeclampsia prevention or as first-line antihypertensive.
– Avoid ACE inhibitors/ARBs and direct renin inhibitors at all stages of pregnancy.

3) Proteinuria management
– Optimize BP. RAAS blockade is contraindicated during pregnancy; consider postpartum resumption if indicated.
– Edema: salt restriction to comfort; cautious diuretic use if symptomatic volume overload.

4) AKI management
– Treat underlying cause; avoid nephrotoxins; hemodynamic support; early delivery if maternal/fetal indications.
– Dialysis for standard indications (refractory volume overload, hyperkalemia, uremic symptoms, severe acidosis), with obstetric input.

5) UTI management
– Early screening and prompt treatment; tailor therapy to culture and local resistance.
– Consider suppressive prophylaxis for recurrent infections after risk–benefit discussion.

6) Dialysis in pregnancy
– For ESRD or severe AKI:
– Increase dialysis intensity/frequency to optimize volume control and solute clearance; many centers use extended or near-daily hemodialysis.
– Monitor maternal electrolytes, acid–base status, and fetal growth; avoid intradialytic hypotension.
– Adjust dry weight progressively with gestational weight gain; supplement water-soluble vitamins.
– Peritoneal dialysis can be continued with adjustments (smaller, more frequent exchanges), mindful of uterine size and peritonitis risk.

7) Kidney transplantation and pregnancy
– Best outcomes when:
– Stable graft function (often creatinine <1.4 mg/dL), minimal proteinuria, well-controlled BP.
– No rejection episodes and stable immunosuppression for at least 6–12 months prior to conception.
– Immunosuppression:
– Generally compatible: prednisone, azathioprine, tacrolimus/cyclosporine (monitor levels).
– Avoid mycophenolate (teratogenic); switch to azathioprine preconception when feasible. Limited pregnancy data for mTOR inhibitors; individualize.
– Monitor for rejection, hypertension, infections, and drug level fluctuations during and after pregnancy.

8) Delivery planning and postpartum care
– Timing and mode of delivery individualized by maternal and fetal status; neuraxial anesthesia considerations with thrombocytopenia or coagulopathy.
– Postpartum:
– BP may rise; continue monitoring and adjust medications (consider breastfeeding compatibility).
– Preeclampsia can develop or worsen postpartum.
– Reassess kidney function and proteinuria at 6–12 weeks; persistent abnormalities may unmask underlying CKD.

SUMMARY

Key points:
1. Pregnancy lowers serum creatinine through increased GFR; creatinine values that appear “normal” outside pregnancy may signal renal dysfunction in pregnancy. Avoid eGFR equations.
2. CKD, hypertension, and proteinuria increase risks of preeclampsia, preterm birth, and maternal kidney function decline; risks escalate with CKD stage.
3. Preeclampsia is a clinical diagnosis after 20 weeks; proteinuria is not required if other end-organ features are present. Delivery is definitive therapy; magnesium sulfate prevents eclampsia in severe disease.
4. AKI in pregnancy requires rapid, multidisciplinary evaluation; etiologies include preeclampsia/HELLP, obstetric hemorrhage/sepsis, and pregnancy-triggered thrombotic microangiopathies.
5. Screen and treat asymptomatic bacteriuria; manage pyelonephritis with inpatient IV antibiotics. Prefer ultrasound for renal imaging.
6. Labetalol and nifedipine are first-line antihypertensives; ACE inhibitors/ARBs and direct renin inhibitors are contraindicated.
7. Dialysis can be intensified to support pregnancy; transplant recipients can have successful pregnancies with careful planning and monitoring.
8. Postpartum follow-up is crucial to reassess kidney function and manage persistent hypertension/proteinuria.

Pregnancy & Kidney Disease Quick Guide:
– Normal pregnancy creatinine is lower; values ≥0.9–1.0 mg/dL often merit evaluation (use local reference ranges).
– Proteinuria ≥300 mg/day (uPCR ≥0.3) is abnormal.
– Ultrasound is the preferred renal imaging.
– Avoid ACEI/ARB/DRI and other teratogens; align meds with breastfeeding plans postpartum.
– Multidisciplinary care optimizes outcomes.

CLINICAL PEARLS

Diagnostic pearls:
– Do not rely on creatinine-based eGFR in pregnancy; follow absolute creatinine and trends.
– Use spot uPCR (or uACR) for initial proteinuria assessment; confirm and monitor consistently with the same method.
– Consider angiogenic markers (sFlt-1/PlGF) when distinguishing CKD relapse from superimposed preeclampsia if locally available.

Management pearls:
– For acute severe hypertension (≥160/110), treat promptly with IV labetalol or hydralazine, or oral immediate-release nifedipine per local protocols.
– Avoid NSAIDs for analgesia in AKI, preeclampsia, or third-trimester pain; acetaminophen is preferred.
– After antepartum pyelonephritis, prophylactic antibiotics can reduce recurrence; individualize.
– In dialysis, prevent intradialytic hypotension to protect uteroplacental perfusion; small, frequent sessions often better tolerated.

When to refer/escalate:
– New creatinine elevation above pregnancy norms, rapidly rising proteinuria, or suspected preeclampsia.
– Refractory hypertension, nephrotic syndrome, suspected GN or TMA, or AKI.
– CKD stage ≥3, heavy proteinuria, or transplant recipients—co-manage with maternal–fetal medicine.

Postpartum checkpoints:
– Reassess BP, creatinine, and proteinuria at 6–12 weeks; persistent abnormalities may indicate underlying CKD.
– Review medication safety for breastfeeding and consider reintroduction of RAAS blockade if indicated.

VISUAL MATERIALS

Proposed figures/tables (to be created):
1. Timeline diagram of physiological renal changes across trimesters (RPF/GFR, creatinine, protein excretion).
2. Algorithm: Evaluation of hypertension and proteinuria after 20 weeks (gestational HTN vs preeclampsia vs CKD flare).
3. Table: Antihypertensives and common nephrology medications—pregnancy and breastfeeding considerations (e.g., labetalol, nifedipine, ACEI/ARB, diuretics, immunosuppressants).
4. Flowchart: Workup of AKI in pregnancy with key branch points (volume status, hemolysis/TMA labs, LFTs, ultrasound).
5. Imaging guide: Nephrolithiasis in pregnancy—ultrasound first, when to consider MR urography, indications for decompression.
6. Dialysis in pregnancy checklist: frequency, volume targets, monitoring, nutrition.

MULTIPLE CHOICE QUESTIONS

1) A 28-year-old at 24 weeks with new BP 148/92 mmHg and uPCR 0.4 g/g has normal platelets and LFTs. Most consistent diagnosis?
A. Chronic hypertension
B. Gestational hypertension
C. Preeclampsia without severe features
D. CKD flare
Correct answer: C
Explanation: New-onset hypertension after 20 weeks with proteinuria (uPCR ≥0.3) meets criteria for preeclampsia without severe features in a previously normotensive patient.

2) Which statement about kidney function in normal pregnancy is most accurate?
A. eGFR equations are reliable for staging CKD during pregnancy
B. Serum creatinine typically increases due to hemodilution
C. GFR increases by ~30–50%, lowering serum creatinine
D. Protein excretion ≥500 mg/day is physiologic
Correct answer: C
Explanation: GFR rises, lowering serum creatinine. eGFR equations are not validated; protein ≥300 mg/day warrants evaluation.

3) A pregnant patient with CKD and baseline proteinuria 1.2 g/day is counseled preconception. Which medication should be stopped before conception due to teratogenicity?
A. Azathioprine
B. Tacrolimus
C. Mycophenolate mofetil
D. Prednisone
Correct answer: C
Explanation: Mycophenolate is teratogenic and should be transitioned (e.g., to azathioprine) prior to conception.

4) First-line imaging for suspected nephrolithiasis at 22 weeks’ gestation:
A. Non-contrast abdominal CT
B. Renal ultrasound
C. Intravenous pyelogram
D. Contrast-enhanced CT urography
Correct answer: B
Explanation: Ultrasound is preferred to avoid ionizing radiation; MR urography can be considered if needed.

5) The best initial antihypertensive choices for chronic hypertension in pregnancy typically include:
A. Lisinopril or losartan
B. Labetalol or nifedipine
C. Aliskiren or candesartan
D. Minoxidil or clonidine routinely
Correct answer: B
Explanation: Labetalol and nifedipine are first-line; ACEI/ARB/DRI are contraindicated.

6) Which finding most strongly supports superimposed preeclampsia over stable CKD in the third trimester?
A. Stable creatinine with persistent baseline proteinuria
B. New thrombocytopenia and rising AST/ALT with hypertension
C. Longstanding proteinuria without BP changes
D. Normal sFlt-1/PlGF ratio when available
Correct answer: B
Explanation: Thrombocytopenia and transaminitis with new/worsening hypertension suggest preeclampsia.

7) In pregnancy-triggered aHUS (often postpartum), which statement is most appropriate?
A. It is best managed expectantly as it resolves spontaneously
B. Plasma exchange is always curative
C. Complement inhibition may be indicated with specialist input
D. Delivery cures the condition immediately
Correct answer: C
Explanation: aHUS is complement-mediated; targeted therapy may be required. Delivery alone may not resolve it.

8) Regarding UTIs in pregnancy, the best statement is:
A. Screening for asymptomatic bacteriuria is unnecessary
B. Nitrofurantoin is always contraindicated
C. Treat asymptomatic bacteriuria to reduce pyelonephritis risk
D. Fluoroquinolones are preferred first-line
Correct answer: C
Explanation: Screening and treatment of asymptomatic bacteriuria reduce pyelonephritis. Nitrofurantoin is generally acceptable except near term in G6PD deficiency; avoid fluoroquinolones.

9) In a hemodialysis-dependent pregnancy, which strategy is most appropriate?
A. Reduce dialysis frequency to avoid hypotension
B. Intensify dialysis sessions to improve solute and volume control
C. Target intradialytic BP nadirs to maximize ultrafiltration
D. Avoid iron and vitamins during pregnancy
Correct answer: B
Explanation: More frequent/extended dialysis improves metabolic and volume control; avoid intradialytic hypotension.

10) Which laboratory threshold in pregnancy should prompt evaluation for renal dysfunction in most settings?
A. Serum creatinine 0.5 mg/dL
B. Serum creatinine 0.8 mg/dL is always abnormal
C. Serum creatinine ≥0.9–1.0 mg/dL in mid–late pregnancy
D. Any detectable protein on dipstick
Correct answer: C
Explanation: Because creatinine declines in pregnancy, values at or above ~0.9–1.0 mg/dL often exceed expected ranges; use local reference intervals and clinical context.

POWERPOINT PRESENTATION

Slide 1: Title – Pregnancy and Kidney Disease
– Scope: physiology, risks, complications, diagnosis, and management
– Audience: postgraduate clinicians; multidisciplinary relevance

Slide 2: Normal Renal Physiology in Pregnancy
– ↑RPF/GFR by 30–50%; ↓serum creatinine/urea
– Physiologic proteinuria and glycosuria
– Hydronephrosis of pregnancy (right > left)

Slide 3: Clinical Implications of Physiology
– Avoid eGFR equations; monitor absolute creatinine
– Pregnancy-specific creatinine thresholds
– Use uPCR/uACR for proteinuria monitoring

Slide 4: CKD and Pregnancy – Risk Stratification
– Risks rise with CKD stage, proteinuria, uncontrolled BP
– Diabetic kidney disease and lupus considerations
– Counseling and co-management essentials

Slide 5: Preeclampsia – Diagnosis and Distinction from CKD
– Diagnostic criteria; severe features
– Role of platelets, LFTs, creatinine, symptoms
– Angiogenic markers where available

Slide 6: Managing Hypertension in Pregnancy
– Targets individualized; urgent therapy for severe BP
– First-line meds: labetalol, nifedipine; avoid ACEI/ARB/DRI
– Diuretics for volume overload, not routine

Slide 7: AKI in Pregnancy – Causes and Approach
– Pregnancy-specific etiologies (preeclampsia/HELLP, aHUS)
– Workup: volume, hemolysis/TMA labs, LFTs, ultrasound
– When to consider biopsy and delivery

Slide 8: UTI and Pyelonephritis
– Screen and treat asymptomatic bacteriuria
– Safe antibiotics; avoid fluoroquinolones/tetracyclines
– Indications for hospitalization

Slide 9: Nephrolithiasis in Pregnancy
– Ultrasound first; MR urography if needed
– Conservative care; urgent decompression when infected/obstructed
– Avoid NSAIDs; acetaminophen preferred

Slide 10: Dialysis and Transplant in Pregnancy
– Intensified dialysis; avoid hypotension; nutrition
– Transplant: timing, stable graft, immunosuppression adjustments
– Close monitoring for rejection and drug levels

Slide 11: Delivery and Postpartum Care
– Individualize timing/mode of delivery
– Postpartum BP rise and preeclampsia risk
– 6–12 week reassessment of renal function and proteinuria

Slide 12: Key Takeaways and Team-Based Care
– Physiology informs thresholds and interpretation
– Multidisciplinary planning improves outcomes
– Safety-first medication strategies

Educational disclaimer: This chapter is for educational purposes for healthcare professionals and does not replace clinical judgment, local protocols, or specialist consultation. Management should be individualized based on patient-specific factors and institutional guidelines.

Visual learning: Pregnancy and Kidney Disease

Presentation resource: The Kidney Hub clinical-series PowerPoint for Chapters 22–30 accompanies these chapters for teaching use.