Numerous anecdotal reports but few scientific approaches have suggested an increase in androgens in early pregnancy. In this study we have compared the concentration of serum androgens, testosterone and androstenedione in early pregnancy, starting within the cycle of conception. We have taken the opportunity to study women with premature ovarian failure where pregnancy develops in the virtual absence of ovarian functions. This study demonstrates that the concentration of testosterone (0.29 +/- 0.04 ng/ml) and androstenedione (1.770 +/- 0.136 ng/ml) in these subjects is as low as, if not lower than, non-pregnant women (0.39 +/- 0.02 and 2.170 +/- 0.025 ng/ml), significantly increased in normal pregnancies (1.190 +/- 0.118 and 3.920 +/- 0.297 ng/ml; P < 0.05) and even further increased in human menopausal gonadotrophin-treated cycles (1.990 +/- 0.230 and 8.19 +/- 0.72 ng/ml; P < 0.05). These studies demonstrate that the ovary is a contributor to the circulating concentrations of testosterone and androstenedione starting within the cycle of conception.