Pregnancy and Your Kidneys

Our body goes through several physiological changes during pregnancy, and the kidney is no exception. During pregnancy, both sodium and water retention increases plasma volume. This increases the blood flow to the kidneys during pregnancy. When there is an increase in blood flow to the kidney, the filtration rate, also known as GFR, will increase up to about 50%. Blood creatinine level, a marker of kidney function, will also decrease during a normal pregnancy due to the increased infiltration rate. If a patient has a high creatinine level during pregnancy, this may be an indication of significant kidney impairment.

Kidneys During Pregnancy

Change #1
Lower Blood Pressure

As blood volume expands during pregnancy, blood pressure begins to decline within the first trimester. It will most likely reach its lowest point during the second trimester because of blood vessel dilation.

Erythropoietin is a hormone (produced in the kidney) which stimulates bone marrow to produce red blood cells. As kidney function declines, erythropoietin production also declines. This can cause some patients to become anemic.  Anemic patients often experience fatigue, weakness, and shortness of breath.

Change #2
More Protein in Urine

The kidneys can also cause an increase in protein excretion during pregnancy. Normally, the maximum value of protein excretion is 100 mg per 24 hours in a non-pregnant patient. However, during pregnancy, this value can increase to approximately 200 mg per 24 hours. Any value greater than 300 mg of protein per 24 hours is abnormal.

Change #3
Increased Kidney Size

Finally, because of the increased blood volume during pregnancy, the kidney size may also increase from 1 to 1.5 cm. The collection system in the kidney may also dilate and potentially lead to an increased risk of infection or asymptomatic bacteriuria. Therefore, screening for bacteria in your urine is recommended early during pregnancy so treatment can be given if necessary.

If you are having any issues with your kidneys during pregnancy, please schedule an appointment at (714) 435-0150 for a consultation!