Oestrogen dose tapering during luteal phase does not affect clinical outcomes after hormone replacement treatment–frozen-thawed embryo transfer cycles: a retrospective analysis

Abstract STUDY QUESTION Does oestrogen dose tapering during the luteal phase affect the clinical outcome after hormone replacement treatment–frozen-thawed embryo transfer (HRT-FET) cycles? SUMMARY ANSWER Our results suggest that tapering oestrogen doses during the luteal phase results in similar clinical outcomes to those obtained with the traditional luteal phase support (LPS). WHAT IS KNOWN ALREADY Traditional LPS with oestrogen and progesterone is considered necessary in HRT-FET cycles. However, case reports have shown successful clinical pregnancies and live births in the absence of oestrogen administration after embryo transfers. STUDY DESIGN, SIZE, DURATION This was a retrospective study on 6035 HRT-FET cycles extending over 7 years from January 2011 to June 2018 at the reproductive medicine centre of Xiangya Hospital. PARTICIPANTS/MATERIALS, SETTING, METHODS We compared the clinical outcomes of 1632 HRT-FET cycles with tapered oestrogen doses from 12 days after embryo transfer (study group) to those of 4403 HRT-FET cycles maintained on constant oestrogen doses during the luteal phase (control group) in the case of positive serum HCG test. MAIN RESULTS AND THE ROLE OF CHANCE We found similar biochemical pregnancy rates (52.1% vs. 51.9, P = 0.864), clinical pregnancy rates (44.9% vs. 43.2%, P = 0.249), implantation rates (29.8% vs. 29.3%, P = 0.591) and miscarriage rates (16.0% vs. 14.6%, P = 0.379) between the studied groups. LIMITATIONS, REASONS FOR CAUTION Retrospective, design-associated biases are possible. In addition, some baseline characteristics differed between groups. Finally, we did not compare live birth rates between groups. WIDER IMPLICATIONS OF THE FINDINGS Our study showing similar outcomes between traditional LPS and oestrogen tapering during the luteal phase indicates that oestrogen may be cautiously tapered during the luteal phase after HRT-FET cycles. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the National Natural Science Foundation of China (grant no. 81401269) and the class General Financial Grant from the China Postdoctoral Science Foundation (grant no. 2017M620360). The authors declare that they have no competing interests. TRIAL REGISTRATION NUMBER N/A