Renal Disease & Pregnancy

Oct 08, 2018

Women with renal disease, also known as kidney disease, continue to be at a significantly increased risk of complications during pregnancy, despite advances in healthcare to reduce these outcomes.

The incidence of renal disease in pregnant women is relatively low with approximately 0.03% of pregnant women who had been diagnosed with the disease prior to conceiving. However, the potential effects are alarming and, as a result, this is a topic that needs to be closely considered.

Stage of Kidney Disease

The stage of the kidney disease in the pregnant woman will also have an effect on the expected outcomes and, predictably, those with more severe disease are more likely to experience complications. The stage of disease is classified by the glomerular filtration rate (GFR).

Stage 1 involves kidney damage with normal or raised GFR, greater than 90.
Stage 2 involves kidney damage with mildly low GFR between 60 and 89.
Stage 3 is characterized by moderately low GFR between 30 and 59.
Stage 4 is characterized by severely low GFR between 15 and 29.
Stage 5 is referred to as kidney failure with GFR less than 15 and the need for dialysis.

Renal Function in Pregnancy

During pregnancy, the glomerular filtration rate normally increases to up to 150% of the normal rate, peaking at approximately the 13th week of pregnancy. In this time, the levels of urea and creatinine decrease as a result of the increase renal excretion.

Changes in hormones levels such as progesterone during pregnancy can also have an effect on renal function, due to the relaxation of smooth muscles in the body. Additionally, the tubular function can reduce the reabsorption of glucose, leading to glycosuria.

Effects on Pregnancy

There are several areas that can be negatively affected in pregnancy if the mother is affected by renal disease. These include pre-term delivery, fetal growth, preeclampsia and perinatal deaths.

The incidence of these effects depends on the stage of renal disease, with complications occurring less commonly in earlier stages of the disease.

The prognosis for infants with mothers that are on dialysis while pregnant is particularly alarming. The majority of associated pregnancies are affected by restricted fetal growth and pre-term birth, and only 75% of infants survive if the mother was on dialysis during the pregnancy. The survival rate is even lower at approximately 50% for infants if the mothers were on dialysis at the time of conception.

Effects on Renal Function

There can also be a loss of renal function linked to pregnancy that occurs during or continues after postpartum.

Approximately half of those with moderate to severe renal disease experience at 25% loss of renal function during pregnancy and the majority of these continue postpartum.

Women with Renal Disease Conceiving

Women with renal disease who are considering pregnancy and to start a family should have access to specialist health advice to help them through the process. It is important that they are aware of potential risks and the ways in which they can reduce complications and improve the prognosis for their child.

Most women with mildly decreased renal function before conceiving have a normal pregnancy without adverse effects, although there is a slightly increased risk of complications. Those with more advanced disease are at an increased risk of complications for their baby and some, particularly for those patients on dialysis, may be fatal for the infant.