BACKGROUND AND OBJECTIVES: For many women pregnancy is the first contact with health services, thus providing an opportunity to identify renal disease. This study compares causes and long-term renal outcomes of biopsy-proven renal disease identified during pregnancy or within 1 year postpartum, with nonpregnant women. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Native renal biopsies (1997-2012), in women of childbearing age (16 to <50 years), from 21 hospitals were studied. The pregnancy-related diagnosis group included those women with abnormal urinalysis/raised creatinine identified during pregnancy or within 1 year postpartum. Pregnancy-related and control biopsies were matched for age and ethnicity (black versus nonblack). RESULTS: One hundred and seventy-three pregnancy-related biopsies (19 antenatal, 154 postpregnancy) were identified and matched with 1000 controls. FSGS was more common in pregnancy-related biopsies (32.4%) than controls (9.7%) (P<0.001) but there were no differences in Columbia classification. Women with a pregnancy-related diagnosis were younger (32.1 versus 34.2 years; P=0.004) and more likely to be black (26.0% versus 13.3%; P<0.001) than controls, although there were no differences in ethnicities in women with FSGS. The pregnancy-related group (excluding antenatal biopsies) was more likely to have a decline in Chronic Kidney Disease Epidemiology Collaboration eGFR in the follow-up period than the control group (odds ratio, 1.67; 95% confidence interval, 1.03 to 2.71; P=0.04), and this decline appeared to be more rapid (-1.33 versus -0.56 ml/min per 1.73 m(2) per year, respectively; P=0.045). However, there were no differences between groups in those who required RRT or who died. CONCLUSIONS: Pregnancy is an opportunity to detect kidney disease. FSGS is more common in women who have been pregnant than in controls, and disease identified in pregnancy or within 1 year postpartum is more likely to show a subsequent decline in renal function. Further work is required to determine whether pregnancy initiates, exacerbates, or reveals renal disease.