Defining poor ovarian response during IVF cycles, in women aged <40 years, and its relationship with treatment outcome.

BACKGROUND

Poor ovarian response limits IVF success but assessing interventions is difficult because of the wide variation in definition. This study attempts to derive objective definitions of poor response.

METHODS

A retrospective study of a consecutive series of 1190 patients aged <40 years undergoing their first IVF/ICSI cycle was undertaken. Factors adversely affecting implantation, including advanced female age, were excluded. Clinical outcome in cycles reaching oocyte retrieval (n = 1036) were evaluated with respect to gonadotrophin dose used and oocyte number. Cancelled cycles (n = 154) were analysed in relation to the stimulation dose at cancellation and outcome of their subsequent cycle.

RESULTS

Cycle cancellation for patients on >/=300 IU FSH/day compared to those on a lower dose was associated with a significantly worse outcome in the subsequent cycle. If <3000 IU FSH/cycle were administered, clinical pregnancy rates remained favourable if <4 eggs were recovered (29 versus 33% for >/=5 eggs). By contrast, if >/=3000 IU FSH was required, the pregnancy rate was 25% if >/=5 eggs were recovered but declined to 7% if <4 were obtained.

CONCLUSIONS

Definitions of poor response should include the degree of ovarian stimulation used. A low oocyte number is only detrimental if the cumulative dose is >3000 IU FSH. Cancellation at >/=300 IU FSH/day is associated with a significantly worse prognosis and could define poor response.