Association of body mass index, age, and cigarette smoking with serum testosterone levels in cycling women undergoing in vitro fertilization

OBJECTIVE: [1] To examine the effects of body mass index (BMI), age, cigarette smoking, cause of infertility, and use of oral contraceptives on baseline serum testosterone (T), and [2] to examine associations between baseline serum T and IVF outcomes such as pre-hCG serum E(2), number of oocytes retrieved, oocyte fertilization rate, and pregnancy outcome in regularly cycling women. DESIGN: Prospective, cohort study. SETTING: Three IVF programs in eastern Massachusetts. PATIENT(S): Four hundred twenty-five regularly cycling women planning to undergo IVF. Women with polycystic ovary syndrome, ovulatory infertility, or irregular cycles were excluded from this study. INTERVENTION(S): Collection of epidemiological data and baseline serum in women undergoing IVF. MAIN OUTCOME MEASURE(S): Baseline serum total T, sex hormone binding globulin (SHBG), and calculation of free androgen index. RESULT(S): Body mass index >26 kg/m(2) was associated with a significant increase in serum T (P<.01) and free androgen index (P<.0001). Serum T decreased significantly throughout the fourth decade of life (P10 pack years was associated with increased serum T (P<.01). A diagnosis of endometriosis was associated with decreased serum T. Serum T correlated positively with pre-hCG serum E(2) and number of oocytes retrieved. However, serum T did not significantly influence fertilization or pregnancy rates. CONCLUSION(S): In cycling infertile women, increasing BMI and cigarette smoking are associated with increased serum T. Advancing age and endometriosis are associated with decreased serum T.