The outlook for pregnancy in gravidas with kidney disorders and the effect of gestation on the remote outcome of the underlying disease remain uncertain, and conception in such women continues to generate anxiety for them as well as their physicians. There is general agreement that a moderately severe decrease in renal function (that is, a serum creatinine concentration in excess of 2 mg/dl), especially in the presence of significant hypertension, reduces drastically the chances for conception, and all the more for a successful outcome of the gestation [1–7]. Women with preserved kidney function and normal blood pressure have an increased incidence of preeclampsia; but except for this complication, the outlook for the pregnancy does not seem to be worse than it is in other gravidas [1–7]. The situation is less clear in regards to the effects of gestation on the mother's kidney disease: Most investigators believe that pregnancy does not affect adversely the natural course of renal disorders as long as kidney function is, at most, mildly impaired and hypertension is absent at conception [1, 3–11]. In contrast, several reports in the older literature (reviewed in Ref. 2) and more recent studies describing mainly patients from Australia maintain that in such women pregnancy often leads to a worsening of the morphologic lesions and a deterioration of renal function [12–15]. The cause of these divergent views is not readily apparent, but it is probably due in no small measure to the lack of studies where the diagnosis was established by renal biopsy and in which clinical, functional, and pathologic observations were correlated in sufficiently large numbers of gravidas studied prospectively. We organized the present study as a joint project between three medical centers with a long-standing interest in the subject, in order to include a large number of patients originating from various types of medical practice and geographic location: The University of Chicago Lying-in Hospital is a perinatal referral center that also serves a large inner-city population; Yale University School of Medicine is a referral center for most of the State of Connecticut; and the Princess Mary Maternity Hospital serves the population of Newcastle-upon-Tyne and the surrounding area of Northern England. Analysis of renal-function profiles and pregnancy outcome was based on the same criteria for patients from all three centers. The gravidas were selected for inclusion in the study by the availability of a biopsy diagnosis, and their course was studied through subsequent gestations, if any, or for various periods until the end of followup. This survey represents therefore a combined prospective and retrospective study that, although not free of some of the shortcomings of earlier reports, we hope contributes useful information on a subject of obvious interest to obstetricians and nephrologists alike.