Objective-The purpose of this study was to investigate maternal plasma concentrations of asymmetric dimethylarginine (ADMA) in mid-pregnancy and at the time of disease in women who develop preeclampsia compared to women with uncomplicated pregnancies and women with SGA infants.Study design-Plasma samples were collected at mid-pregnancy and at the time of delivery from 31 women with uncomplicated pregnancies, 12 women with SGA infants and 15 women with preeclampsia. ADMA and L-arginine were measured by high-pressure liquid chromatography. Conclusions-Maternal ADMA concentrations are higher in mid-pregnancy in women who develop preeclampsia compared to uncomplicated controls and SGA. Elevated ADMA prior to clinical onset of preeclampsia suggests a role of this NOS inhibitor in the pathophysiology of preeclampsia. Results-Maternal

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