Introduction
Kidneys are the major organs involved in the filtration of the blood, maintaining the electrolyte and acid-base balance in the body. Any disease or disorder affecting the kidneys would definitely produce a big impact on the life of a person. It becomes even more difficult when a patient with improperly functioning kidneys gets pregnant. Pregnancy with pre-existing kidney disease is a challenging situation for both the patient as well as the physician because of the increased demand for the kidney for maternal blood filtration, the risk of teratogenicity of the drugs, and the increased chances of complications associated. Hence, the journey of pregnancy in those cases should be accompanied by an interdisciplinary team to ensure good maternal and fetal health.
What Does the Term Pregnancy Denote?
The term pregnancy indicates the period or the time in which the fetus develops inside the mother's womb or the uterus. It is usually calculated from the date of the last menstrual period and lasts about 40 weeks or nine months. The journey and the symptoms of pregnancy vary from person to person.
It is important to understand the normal physiological changes in pregnancy, as this would help in framing the diagnosis as well as the treatment modalities. The physiological, as well as anatomic changes in the woman's body start to appear during the early stages of the first trimester of pregnancy. A good understanding of the normal changes during pregnancy is important as this would help in framing the diagnosis as well as the treatment modalities.
What Are the Physiological Changes Seen in Pregnancy?
Various physiological changes occur during pregnancy, such as;
Hemodynamic Changes:
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Increased cardiac output.
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Decreased systemic blood pressure.
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Decreased vascular resistance.
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Increased nitric oxide levels in the blood.
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Increased levels of relaxin in the blood.
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Increased progesterone levels.
Volume Changes:
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Increased plasma volume of 40 to 50%.
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Increased total body water content.
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Decreased plasma osmolality by 10 mOsm/kg.
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Decreased plasma albumin.
Changes in Acid-Base Balance:
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Increased blood pH 7. 42–7. 44.
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Mild respiratory alkalosis.
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Increased bicarbonate reabsorption.
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Decreased serum hydrogen ion.
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Decreased PCO2 (18 to 22 mEq/L).
Hormonal Changes:
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The decreased osmotic threshold for thirst.
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Increased metabolic clearance.
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Increased levels of vasopressin, aldosterone, mineralocorticoids, etc.
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Increased renal kallikrein excretion.
What Are the Physiological and Anatomical Renal Changes that Occur in Pregnancy?
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Increased renal size and volume.
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Dilatation of the collecting duct.
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Ureteral connective tissue hyperplasia.
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Ureteral smooth muscle hypertrophy.
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Physiologic hydronephrosis can happen due to the enlarging uterus putting pressure on the kidneys.
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Urine retention also happens due to hydronephrosis.
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Increased urinary protein excretion (proteinuria) to a range of 180 to 250 mg/day.
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A 50% increase in glomerular filtration rate happens in the second trimester. This results in hyperfiltration, thereby reducing the serum creatinine levels to a range of 0.4 to 0.6 mg/dl.
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A 50 to 80% increase in renal blood flow.
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Decrease in renal vascular resistance.
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Hyperfiltration of sugar, amino acids, vitamins, proteins, etc.
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Positive sodium balance.
What Are the Complications of Pre-existing Kidney Disease in Pregnant Women?
Studies report that the incidence of women getting pregnant with pre-existing renal diseases has increased in recent years, with a reported incidence of 15,000 to 20,000 pregnancies per year in England. The most common cause of chronic kidney disease in those patients is attributed to the fact that women pursue pregnancy at more advanced ages. Although pre-existing kidney disease is not an obstacle to reproduction in women, it is associated with high chances of maternal and fetal complications. Research shows that women under dialysis for more than a year would lose their ability to become pregnant as their menstrual cycle becomes irregular or absent.
The most common kidney diseases reported in pregnant women include:
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IgA nephropathy.
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Chronic kidney disease.
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End-stage renal disease.
How Does Hypertension Affect Pregnant Women With Pre-existing Kidney Disease?
Women with a known history of hypertension prior to pregnancy are at increased risk of developing preeclampsia (a condition in which the blood pressure value is greater than 140/90 mmHg). This preeclampsia, in turn, would result in proteinuria (increased excretion of protein in the urine of more than 300 mg/day) and increased serum creatinine concentration.
Complications:
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Impaired angiogenesis (blood vessel formation) in the fetus.
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Seizures may develop in mothers in cases of uncontrolled hypertension.
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Fetal death.
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Preterm delivery.
Management:
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Reduce the salt intake.
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Use of Antihypertensives (to control blood pressure levels).
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Emergency C-sections are indicated in cases of severe preeclampsia to prevent fetal complications.
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Full-term delivery in cases of mild and controllable hypertension.
What Are the Complications of Lupus Nephritis in Pregnant Women?
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The occurrence of systemic lupus erythematosus (SLE) in the kidney is called lupus nephritis. It is mainly due to the immunological changes that occur in the body resulting in the production of autoantibodies. Women with a known history of lupus nephritis should take advice from their physician prior to conception, and they should have at least a six-month quiescent period prior to pregnancy.
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Studies report that the patients with renal symptoms demonstrated anti-DNA antibodies and low C3 levels. Patients who developed lupus nephritis in the second and trimester of pregnancy demonstrated low C4 levels and high anti-C1 q antibodies.
Diagnosis:
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Diagnosis of this condition is established by the detection of antinuclear antibodies in the patient's serum.
Complications:
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High risk of preterm delivery.
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High chances of developing preeclampsia.
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The estimated overall mortality rate is one percent.
Treatment:
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Close Monitoring - Patients should be monitored carefully to diagnose any disease flares and to prevent further adverse complications.
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Medications - Safer drugs should be prescribed to prevent any adverse effects. Drugs such as Hydroxychloroquinone and Azathioprine can be used to suppress the autoantibodies.
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Renal Function Tests and Biomarkers - Should be used often to check whether the disease is under control.
What Are the Complications of IgA Nephropathy in Pregnant Women?
IgA nephropathy is characterized by the deposition of IgA antibodies in the kidney, affecting normal kidney function.
Complications:
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Pregnancy loss.
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Preeclampsia.
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Low birth weight babies.
Treatment:
Patients with mild IgA nephropathy usually do not require any treatment; in patients with severe disease conditions, safer immunosuppressive agents should be prescribed.
What Are the Complications of Chronic Kidney Disease in Pregnant Women?
Chronic kidney disease is characterized by the improper functioning of the kidneys, which lasts for a longer period of time. Women with an antepartum renal disease with serum creatinine levels of more than 2 mg/dl are at a higher risk of renal failure.
Causes:
It may occur as a result of pre-existing diseases such as diabetes, lupus nephritis, hypertension, etc.
Complications:
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Decreased renal function.
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Preterm delivery.
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HELLP syndrome (It is a serious complication of pregnancy that mainly affects the blood and the liver).
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Still birts.
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Neonatal death.
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Low birth weight.
Treatment:
The main aim of treatment is to treat the underlying disease to prevent the further progression of renal disease. The patient should be informed priorly to the complications of pregnancy with the pre-existing renal disease. Careful monitoring and neonatal care would help improve the survival rates.
What Are the Complications of End-Stage Renal Disease (ESRD) in Pregnant Women?
Pregnant women with the end-stage renal disease require dialysis. Studies report that patients under dialysis have diminished fertility rates due to irregular or absent menstrual periods. However, during the first year of dialysis, the chances of women getting pregnant are comparatively high.
Causes:
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ESRD in pregnant women is a rare complication, but if it occurs, it can be caused due to underlying systemic diseases such as poorly controlled diabetes, hypertension, lupus nephritis, autoimmune conditions, etc.
Complications:
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High mortality rates.
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Fetal death.
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Preterm delivery.
Treatment:
Intensive dialysis is the mainstay of treatment in pregnant women with end-stage renal disease.
Conclusion
Pregnancy with pre-existing kidney disease is a major challenge to both the patient as well as the medical care provider. Women with pre-existing kidney disease should consult their respective care providers and take their advice before planning the pregnancy. Certain medical conditions need prophylactic measures before pregnancy that should be followed strictly to improve maternal and fetal incomes.
