Intrauterine growth restriction (IUGR) is the leading cause of fetal mortality and morbidity. As an etiology, each of placental findings, maternal factors and fetal factors has been reported to be associated with IUGR, although a comprehensive approach to examine all of these parameters as a cause of IUGR has not been reported. In the present study, therefore, we comprehensively examined the placental findings and maternal and fetal factors in the cases of IUGR (n=257, mean maternal age, 30 years; gestational weeks, 34 weeks) and normal growth pregnancies (n=258, mean maternal age, 30 years; gestational weeks, 33 weeks), and determined risk factors for IUGR. The prevalence of pregnancy hypertension (PHT) (19% vs. 8%, P<0.01), smoking habit (3% vs. 0.7%, P<0.05) and fetal anomaly (3.5% vs. 0.8%, P<0.05) were higher in IUGR cases than normal growth pregnancies. Pathologically, the prevalence of infarction (33% vs. 14%, P<0.05), fetal vessel thrombosis (22% vs. 6%, P<0.001) and chronic villitis (11% vs. 3%, P<0.001) were higher in IUGR cases than those in normal growth pregnancies. A multivariable regression analysis revealed that maternal factors (PHT), fetal factors (anomaly), and placental findings (infarction, fetal vessel thrombosis, and chronic villitis) are independently associated with increased risk of IUGR (all P<0.01).