SummaryBackground and objectives CKD and multiple pregnancies bear important risks for pregnancy outcomes. The aim of the study was to define the risk for adverse pregnancy-related outcomes in multiple pregnancies in CKD patients in comparison with a control group of "low-risk" multiple pregnancies.Design, setting, participants, & measurements The study was performed in the Maternal Hospital of the University of Turin, Italy. Of 314 pregnancies referred in CKD (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011), 20 were multiple (15 twin deliveries). Control groups consisted of 379 low-risk multiple pregnancies (314 twin deliveries) and 19 (15 twin deliveries) cases with hypertension-collagen diseases. Baseline data and outcomes were compared by univariate and logistic regression analyses.Results The prevalence of multiple pregnancies was relatively high in the CKD population (6.4%); all referred cases were in early CKD stages (I-II); both creatinine (0.68 to 0.79 mg/dl; P50.010) and proteinuria (0.81 to 3.42 g/d; P50.041) significantly increased from referral to delivery. No significant difference in demographic data at baseline was found between cases and low-risk controls. CKD was associated with higher risk of adverse pregnancy outcomes versus low-risk twin pregnancies. Statistical significance was reached for preterm delivery (,34 weeks: 60% vs 26.4%; P50.005; ,32 weeks: 53.3% vs 12.7%; P,0.001), small for gestational age babies (28.6% vs 8.1%; P,0.001), need for Neonatal Intensive Care Unit (60% vs 12.7%; P,0.001), weight discordance between twins (40% vs 17.8%; P50.032), and neonatal and perinatal mortality (6.6% vs 0.8%; P50.032).Conclusion This study suggests that maternal-fetal risks are increased in multiple pregnancies in the early CKD stages.