CYP3A4 and preeclampsia: To investigate the association between inter-individual variation in steroidal PRH exposure and CYP3A activity during pregnancy in humans, correlations between circulating concentrations of E1, E2, P4, and CRT and 4β-OH-CHO biomarkers of CYP3A activity in maternal plasma (healthy pregnant and preeclampsia groups combined) were evaluated (Figure 3).