The Effect of Pregnancy on Renal Function in Women

The effect of pregnancy on the renal function of patients with essential hypertension or chronic glomerulonephritis has been the object of the investigation to be reported here. The study has involved the application of renal clearance methods to a group of patients, during their pregnancies and repeatedly during the 1 to 4 years after their delivery. In 3 patients, the series of records includes also observations made before conception. Such repeated studies were designed firstly to demonstrate the immediate changes in renal function developing during the period of gestation; and secondly, to determine whether, after pregnancy is over, there has occurred any significant acceleration in the course of the primary disease. These patients with pre-existing renal or vascular disease are to be contrasted with the cases of specific "toxemia" or eclampsia, upon which we have previously published observations. In our first report on this subject, studies based upon inulin and diodrast clearances showed that the glomerular filtration rate, effective renal blood flow, and tubular excretory mass were unaffected in normal pregnancy (1). In a second paper (2), it was shown that in patients with specific toxemia, the glomerular filtration rate was slightly diminished and the effective renal blood flow increased during the latter part of pregnancy. Following delivery, the blood flow became normal in about half of these patients, while in the others it fell to levels indicative of slight renal ischemia. The latter trend occurred in those women in whom hypertension became permanently established after their attack of toxemia of pregnancy. These observations are in general similar to the