Effect of estrogen priming through luteal phase and stimulation phase in poor responders in in-vitro fertilization

To verify whether a novel protocol administering E₂ during the luteal phase of the preceding cycle and during ovarian stimulation in GnRH antagonist cycle could enhance follicular response and hence improve outcomes in poor responders.

In this retrospective analysis, a total of 155 poor responder patients subjected to IVF/ICSI were analyzed. All the patients had history of more than one prior IVF cycle failure with poor response (less than 5 oocytes retrieved and/or maximal E₂ level less than 500 pg/mL) by using conventional long agonist or antagonist protocol. In luteal E2 treatment protocol (n = 86), oral estradiol valerate 4 mg/day was initiated on luteal day 21 and either stopped at menstrual cycle day 3 (Protocol A, n = 28) or continued during the period of ovarian stimulation until the day of hCG injection (Protocol B, n = 58). IVF parameters and pregnancy outcome of luteal E2 treatments group were compared with a standard GnRH antagonist protocol (n = 69) which the patients received no hormonal pretreatment.

Compared to standard GnRH antagonist protocol, cancellation rate was lower with luteal E2 group (15.1% vs 37.7%, p < 0.01). Moreover, patients treated with luteal estrogen resulted in an increased number of oocytes retrieved (4.5 ± 2.9 vs 3.2 ± 1.9; p < 0.01). A trend toward increase in number of normally fertilized embryos (2.9 ± 2.1vs 2.3 ± 1.9; p = 0.043), and increased prevalence of good quality embryos (51.2% vs 25%; p = 0.047) were noted. Comparing protocol A and B, there were no significant difference between embryologic data, however there were slight increase in ongoing pregnancy rate in protocol B compared to A (27.1% vs 20%, p = 0.357), although statistical significance was not achieved.

Estrogen priming through luteal phase and stimulation phase improved ovarian responsiveness and this may lead to an increase in pregnancy rate in poor responders with failed cycle.