C4A and preeclampsia: measured C3a, C4a and C5a in amniotic fluid in mid-gestation and found significantly higher C3a levels in women who later developed early-onset preeclampsia (<34 weeks) compared to controls (318.7 ng/mL vs. 254.5 ng/mL, P=0.04), while C4a and C5a levels did not differ significantly (86).