Abstract: Objective To investigate the differential expression of adrenomedullin(ADM)in the placentas of women with normal and preeclamptic pregnancies,and explore the importance of ADM and its signal pathway in the development of preeclampsia.Methods Ten pregnant women complicated with preeclampsia during the late term(≥35 wk)were selected for this study along with 7 normal control pregnant women(≥39 wk).The total RNA was extracted and sections of fresh placental tissues were prepared,and ADM expressions at mRNA and protein levels in women with normal and preeclamptic pregnancies were determined by Northern blotting and immunohistochemistry,respectively.Result and Conclusion At both mRNA and protein levels,the expression of ADM in the placentas of preeclamptic women was significantly reduced obviously as compared with that of the normal control(P<0.05),suggesting that ADM expression reduction in preeclamptic placenta might be associated with the development of preeclampsia.