HMGB1 and preeclampsia: Early-onset preeclampsia patients had mean serum HMGB1 levels of 1280.7 ± 691.3 ng/mL, which was not statistically different from the control group (p = 0.096). Mean serum HMGB1 levels in preeclampsia women with severe feature or non-severe feature were comparable (Table 3).