INTRODUCTION: The aim of this study was to identify predictive factors of urolithiasis etiology for acute renal colic (ARC) during pregnancy. MATERIALS AND METHODS: We performed a retrospective review of all pregnant women hospitalized for an ARC between January 2007 and October 2012 in the department of Obstetrics and Gynecology of a University Hospital. Univariate and multivariate regression models were used to assess potential predictive factors of urolithiasis etiology. RESULTS: We included 82 patients. A urolithiasis was identified in 24 (29.3%) patients. In univariate analysis, we identified the following predictive factors for a urolithiasis etiology: primiparity (p = 0.017), leukocyturia (p = 0.021), left hydronephrosis > 10 mm and > 15 mm (p = 0.009; p = 0.02) and right hydronephrosis > 15 mm (p = 0.019). In multivariate analysis, only left hydronephrosis > 10 mm remained predictive for a urolithiasis etiology (p = 0.036; HR 7.45). A ureteral stenting was necessary for 23 patients (28.0%). Three patients (3.7%) had a premature membrane rupture and two patients (2.4%) delivered prematurely. After delivery, 10 patients (12.2%) required surgical treatment. CONCLUSION: Left hydronephrosis was related to urolithiasic etiology for ARC. Obstetrical consequences of ARC were minor.