Steroid anomalies and pregnancy

Partial blockages, which occur at each step catalyzed by cytochrome p450 (CYP) dependent enzymes, presumably explain the finding of low maternal serum unconjugated estriol (uE3) during pregnancies with an affected fetus. Impaired aromatization of fetal androgens may also help explain why some mothers experience maternal virilization during pregnancy with an affected fetus. Impaired aromatization of fetal androgens may also contribute to the virilization of affected female infants. The proposed alternative (or "backdoor") pathway of androgen synthesis, which is believed to be active only during fetal life, is also illustrated. This alternative pathway has been proposed as an explanation for ambiguous genitalia present in some affected females. Note: It is unknown if low maternal serum concentration of uE3 is a consistent finding among all individuals with cytochrome P450 oxidoreductase deficiency.