Pregnancy in Chronic Kidney Disease: Renal, Maternal and Fetal Outcomes

Abstract

The kidneys undergo pronounced haemodynamic, renal tubular, and endocrine changes during pregnancy. During healthy pregnancy the kidney increases production of erythropoietin, active vitamin D, and rennin. Women with chronic kidney disease are less able to make the renal adaptations needed for a healthy pregnancy. In 2002, the Kidney Disease Outcomes Quality Initiative (KDOQI) published a new chronic kidney disease (CKD) classification based on five categories of estimated glomerular filtration rate (eGFR). Before 2002, renal insufficiency is classified as mild, moderate, or severe according to serumcreatinine values from 1,4 to 3,5 mg/dL and serum creatinine only had been used as cut-off . The exact incidence of chronic renal disease could not be ascertained in pregnancy . There are several possible reasons for why chronic renal insufficiency is uncommonly associated with pregnancy. First and foremost is the fact that many women with significant renal insufficiency or renal failure are either beyond childbearing age or infertile. Another important reason may be incomplete reporting or data collection. Finally, the incidence of mild renal disease is often not included in many of the reported series. Diagnosis of the cause of renal disease during pregnancy can be conducted with serologic,functional, and ultrasonographic testing . Renal biopsy is rarely performed during gestation. Proteinuria commonly reflects the degree of kidney damage but also holds prognostic value for progression of kidney disease. Fertility is diminished in women with chronic kidney disease (CKD), especially in those with serum creatinine>3.0 mg/dL or who are dialysis dependent. CKD leads to impairment in the hypothalamic–pituitary–gonadal axis, causing decreased fertility. If patients with CKD (regardless of underlying etiology) become pregnant, they are at increased risk for adverse maternal and fetal outcomes. This risk depends on the severity of baseline renal dysfunction, presence of uncontrolled hypertension, and degree of proteinuria.Women with preexisting mild CKD (stages 1-2), normal blood pressure, and no proteinuria generally have good maternal and fetal outcomes. Patients with moderate (stages3-4) or severe (stage 5) CKD have significantly increased risk of developing worsening renal function, proteinuria, hypertension, as well as increased rates of fetal complications. The combined presence of GFR <40 mL/min/1.73 m2 (CKD stage 3) and proteinuria >1 g/d before conception predicted faster GFR loss after delivery, shorter time to dialysis, and low birth weight.