Age-specific levels for basal follicle-stimulating hormone assessment of ovarian function

Traditionally, the most important measurement in the assessment of ovarian function has been age-independent baseline follicle-stimulating hormone (FSH) levels. The objective of this study was to characterize the continuum of ovarian function based on age-specific categories of baseline FSH.

In a cross-sectional historical cohort study we evaluated records of 434 patients with baseline FSH levels of less than 12 milli international units/mL that underwent ovulation induction for in vitro fertilization (IVF) with long gonadotropin-releasing hormone (GnRH) antagonist or GnRH agonist suppression and modal gonadotropin stimulation of 300 units of gonadotropins per day. In these patients with apparent normal ovarian function by current baseline FSH criteria and with routine ovarian stimulation, we assessed IVF cycle outcomes, including oocyte yields, based on age-specific baseline FSH levels, defined as levels less than or equal to the 95% confidence interval for each age group.

Age-specific baseline FSH levels predicted the retrieval of fewer than or equal to four oocytes, with a positive predictive value of 19.5% and a negative predictive value of 88%. The Mantel-Haenszel common odds ratio for fewer than or equal to 4 oocyte production in the presence of premature ovarian aging was 2.8 (95% confidence interval 1.52-5.17; P<.001).

These results suggest that, within generally accepted normal baseline FSH values, women with baseline FSH above the 95% confidence limits for age produce fewer oocytes in response to normal ovulation induction protocols compared with other women their age.