HMOX1 and preeclampsia: They recruited 10 healthy pregnant women, 9 women with mild preeclampsia, and 12 women with severe preeclampsia and found that higher serum HO-1 levels were found in women with severe preeclampsia (5.5 ± 1.5 ng/mL) compared with the other groups (3.0 ± 0.7 and 3.1 ± 1.6 ng/mL, respectively, mild and healthy pregnant).