The production, transport and metabolism of androgens in normal pregnant women will be reviewed here. This information will serve as a background for the discussion of hyperandrogenism during pregnancy. (See "Causes of gestational hyperandrogenism" and "Diagnosis and management of gestational hyperandrogenism".)
The serum concentrations of some, but not all, androgens increase during normal pregnancy [1-5].
Total testosterone — The serum total testosterone concentration increases progressively throughout pregnancy (figure 1) [1,2,5], an effect that is due primarily to a progressive estrogen-induced increase in serum sex hormone-binding globulin (SHBG) concentrations [4-9]. The increase in testosterone concentration in normal pregnancies occurs as early as 15 days after the LH surge, implying luteal phase ovarian production rather than adrenal production .
There are few studies of androgen production and clearance in normal pregnant women. One study of five pregnant women found that the production rates of testosterone and dihydrotestosterone were similar to those of nonpregnant women, but that testosterone conversion to dihydrotestosterone and the metabolic clearance rates of the two androgens were lower in pregnancy, as would be expected since serum SHBG concentrations are increased . Another study including 1343 women with singleton pregnancies observed that maternal age over 30 years and multiparity were associated with lower androgen levels in pregnancy while smoking was associated with higher androgen levels in the first half of pregnancy compared with younger women, nulliparous women, and nonsmokers, respectively .
Maternal serum testosterone concentrations are three to four times higher than umbilical cord serum concentrations; maternal values are 100 to 140 ng/dL (3.5 to 4.8 nmol/L) and cord values average 33.5 ng/dL (1.2 nmol/L) .