Objective To analyze the risk factors of urolithiasis in pregnancy and the relationship between urolithiasis in pregnancy and pregnancy outcomes.Methods From January 2004 to December 2009,the clinical data of 162 pregnant women (Group A),diagnosed as upper urinary tract calculi,were reviewed,retrospectively.Their age ranged from 18 to 41 years (mean 24±5 years).Seven of them had history of urolithiasis before pregnant.At the same time,150 pregnant women without urinary stone (Group B) were also included in this study,whose mean age was 23±5 years.In addition,150 women without pregnant and urinary stone (Group C) were included in this study,whose mean age was 24±4 years.The blood and urine routine results,blood uric acid and electrolytes were recorded and compared among those groups.In group A,119 cases had symptomatic urolithiasis.Surgical intervention was performed in 24 cases and the conservative therapy was performed in 95 cases.The rates of abortion,premature delivery and cesarean delivery were compared between two groups.Results Compared group A with group B and group C,there were significant differences in the urine WBC (145.16±202.18 vs.46.00± 119.50 and 55.33 ± 145.36 per high power lens) and urine ketone body (2.41 ± 6.14 mmol/L vs.0.30± 1.75 mmol/L and 0.17± 1.26 mmol/L) (P＜0.05).Meanwhile,there were significant differences in the blood leukocytes [(11.39±3.89)× 109/L,(10.78±2.98) ×109/L vs.(6.21±1.48) × 109/L],the blood uric acid (331.12±215.22 μmol/L,329.32± 88.50 μmol/L vs.280.01±69.88 μmol/L),the urine protein (0.29±2.00 mmol/L,0.10±0.19 mmol/L vs.0.02±0.09 mmol/L),urine glucose (2.50±8.44 mmoL/L,2.35±8.63 mmol/L vs.0.25± 1.97 mmol/L) and urine erythrocyte (76.60±98.11,77.43±71.00 vs.13.77±37.93 per high power lens) (P＜0.05).In those patients with symptomatic urolithiasis,there was 1 case of abortion in the conservative treatment and surgery intervention groups,respectively.The premature delivery rate and cesarean delivery rate were 5.3％ vs.0％ and 17.9％ vs.4.2％,respectively.Conclusions The blood leukocytes,blood uric acid,urine protein,urine glucose and urine erythrocytes are significantly high in pregnant women than those in non-pregnant women.However,the relationship between those abnormality and urolithiasis in pregnancy is still indefinite.Since the urine leukocytes and ketone increase obviously,it might suggest that the occurrence of the urine calculi is related with the metabolism of nourishment and electrolytes,urinary tract infection in pregnancy.The surgery intervention may be a risk of fetus miscarriage.