Endometrial advancement after triggering with recombinant or urinary HCG: a randomized controlled pilot study

More than 3 days’ luteal endometrial advancement in IVF has been related with no pregnancies. This study assessed the effect of recombinant and urinary human chorionic gonadotrophin (recHCG and uHCG) when administered for final oocyte maturation on the advancement of endometrial histology. Thirty patients were randomized to receive either 250 μg recHCG or 10,000 IU uHCG in an antagonist/recombinant FSH protocol. Endometrial biopsy was performed on the day of oocyte retrieval. All specimens were evaluated according to Noyes’ criteria by one pathologist blinded to the allocation treatment groups. Single blastocyst transfer was performed. Overall, 13 patients in recHCG group and 14 patients in uHCG group underwent endometrial biopsy. The mean days of histological endometrial advancement were comparable between the two groups: 2.03 versus 2.17 days, respectively. Nevertheless more patients (69%, 9/13) had less than 3 days’ advanced endometrium in the recHCG arm as compared with 43% (6/14) patients in the uHCG group (OR 3.00, 95% CI 0.4–16.3). The delivery rate per patient was higher, although not significantly, in the recHCG group (38.5% versus 28.6%). Both recHCG and uHCG preparations induce advancement of endometrial maturation. Whether a subtle difference in endometrial maturation affects the reproductive outcome remains to be proven.