Kidney disease refers to a condition where the kidneys, responsible for filtering waste products and excess fluids from the blood, become damaged and unable to perform their functions effectively. When pregnancy occurs in individuals with pre-existing kidney conditions, it introduces physiological changes that can interact with the kidneys. Understanding this relationship is important for both the pregnant individual and the developing baby.
Effects of Kidney Disease on Pregnancy Outcomes
Pre-existing kidney disease can significantly influence pregnancy outcomes for both the mother and the baby. One common maternal risk is the development or worsening of hypertension, or high blood pressure, which affects 20-50% of pregnant individuals with chronic kidney disease (CKD). Hypertension can manifest at any point during pregnancy.
The presence of kidney disease also raises the risk of pre-eclampsia, a serious complication characterized by new-onset high blood pressure and signs of organ damage. This condition appears in the second half of pregnancy and may present with symptoms like headaches, blurred vision, or swelling in the hands, feet, or face. Individuals with kidney disease have a 33% increased likelihood of delivering via Cesarean section compared to those without kidney disease.
For the baby, kidney disease in the mother increases the risk of preterm birth, defined as delivery before 37 weeks of gestation. Babies born to mothers with kidney disease have a 52% increased chance of preterm birth. Additionally, these babies are more likely to have a low birth weight (two-fold increased odds) and may be small for their gestational age. Such outcomes can occur due to reduced blood flow through the placenta or maternal complications, potentially leading to NICU admissions or infant death.
How Pregnancy Can Affect Kidney Health
Pregnancy naturally induces several physiological adjustments in the body, which can impact existing kidney conditions. A significant change involves an increase in blood volume and an elevated glomerular filtration rate (GFR). GFR measures how well the kidneys are filtering blood, and while its natural rise during pregnancy is normal, it can place additional strain on kidneys that are already compromised.
This added burden may cause chronic kidney disease (CKD) to worsen during pregnancy, particularly in more advanced stages. Research indicates that pregnant individuals with stage 3a CKD may experience significant kidney function decline, with more advanced stages (4-5 CKD) experiencing a greater decline than earlier stages (3a CKD). The progression of kidney disease during pregnancy is unpredictable, but generally, better kidney function at the start of pregnancy is associated with a lower likelihood of decline.
Individuals with higher levels of protein in their urine, a condition known as proteinuria, at the beginning of pregnancy also face an increased risk of worsening kidney function later in gestation. Acute kidney injury (AKI), a sudden decline in kidney function, might occur. These interactions highlight the complex interplay between pregnancy and kidney health.
Navigating Pregnancy with Kidney Disease
Planning and managing a pregnancy with kidney disease requires a structured and collaborative approach to promote positive outcomes. Before conception, individuals should consult with healthcare providers, including a nephrologist and an obstetrician, for pre-conception counseling. This allows for assessment of kidney function, discussion of risks, and optimization of health, including medication review for pregnancy safety.
Throughout the pregnancy, a multidisciplinary team approach is recommended, involving nephrologists, high-risk obstetricians, and other specialists. This collaborative care ensures comprehensive management and swift responses to any emerging complications. Regular monitoring is an important aspect of care, including frequent blood pressure checks, urine tests for protein and signs of infection, and periodic kidney function tests like serum creatinine and GFR measurements.
Medication management is reviewed and adjusted to ensure safety for the developing baby. For instance, certain blood pressure medications, such as ACE inhibitors and angiotensin receptor blockers, are discontinued due to risks of fetal growth restriction and kidney issues. Low-dose aspirin may be prescribed from 12 weeks of gestation to reduce the risk of pre-eclampsia. Dietary considerations, such as managing salt intake to control blood pressure and fluid balance, are advised.
Delivery planning involves discussions about the timing and method of birth, determined based on the severity of kidney disease and overall health. Most individuals with kidney disease or a kidney transplant can have a vaginal delivery, but a Cesarean section may be necessary if complications arise. Postpartum monitoring is important to assess kidney function recovery or disease progression.