Endocrine determinants of fertility: serum androgen concentrations during follow-up of adolescents into the third decade of life.

We have completed a 13-yr longitudinal study of endocrine features in females originally aged 7-17 yr and report now factors related to fertility in these women, mainly serum testosterone (T) and androstenedione (A) concentrations in relation to becoming pregnant. Longitudinal regression analysis, corrected for the effect of age, showed that current serum T and A concentrations are correlated with those measured 12 yr earlier (T: r = 0.47, P less than 0.01; A: r = 0.57, P less than 0.001). Age-adjusted serum T and A concentrations before any pregnancies were higher in women who subsequently had no pregnancies than in those who had been pregnant (T: never pregnant, mean +/- SEM, 1.10 +/- 0.06 nmol/L, pregnant 0.81 +/- 0.07 nmol/L, P = 0.004; A: never pregnant 4.00 +/- 0.28 nmol/L, pregnant 2.98 +/- 0.33 nmol/L, P = 0.03). Serum androgen concentrations were not related to variables reflecting sexual behavior and the use of oral contraception. The data therefore show that adolescent serum androgen concentrations are preserved into adulthood and are reflected in fertility patterns during the third decade of life. Higher serum androgen concentrations are associated with lower fertility. Together with our previous findings, these data demonstrate that endocrine characteristics formed during puberty seem to persist at least until 30 yr of age.