MMP1 and preeclampsia: The levels of MMP-1 in the umbilical serum of the normal, gestational hypertension, mild preeclampsia and severe preeclampsia groups were 294.33±11.53, 247.78±20.32, 177.67±12.63 and 124.68±15.41 pg/ml, respectively, and there were significant differences between each two groups (P<0.05).