The plasma concentration of deoxycorticosterone (DOC) was determined serially in a large group of primigravid women from 10 weeks' gestation to term. The plasma level of DOC in women whose pregnancies were uncomplicated (n = 44) was 234 +/- 33 pg/ml (mean +/- SE), at 10 to 14 weeks' gestation, a level two times that of nonpregnant subjects. The plasma level of DOC in these women rose to 778 +/- 65 pg/ml at 23 to 26 weeks' gestation, and at term (39 to 42 weeks) was 1,309 +/- 155 pg/ml. The plasma levels of DOC in women (n = 31) who eventually developed pregnancy-induced hypertension (PIH) were similar to those in the women who remained normal at all stages of pregnancy. We also found that, in women with normal pregnancies as well as in all stages of pregnancy. We also found that, in women with normal pregnancies as well as in women destined to develop PIH, the plasma concentration of DOC fluctuated in a manner parallel to that of progesterone throughout gestation; however, changes in the plasma level of DOC did not mirror those of cortisol. These data suggest that excessive plasma levels of DOC are not necessarily associated with the development of PIH. These data also support the view that, in pregnant women, a fraction of circulating DOC may arise via extra-adrenal 21-hydroxylation of progesterone rather than through adrenal secretion.