Causal inference indicates that poor responders have similar outcomes with the antagonist protocol compared with flare

Objective To use causal inference to investigate whether the flare or antagonist protocol is better for poor responders going through controlled ovarian stimulation.

Design A retrospective study.

Setting Retrieval cycles from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System.

Patients Patients in the United States underwent autologous in vitro fertilization cycles from 2014 to 2019 using either the flare or antagonist protocol.

Intervention Not applicable.

Main Outcome Measure Primary outcomes included oocytes retrieved, fertilized oocytes (2PNs), blastocysts, the cumulative live birth rate (CLBR), and cycle cancelation rate.

Results After propensity score matching, patients with a predicted poor response (antimüllerian hormone, <0.5) on their first in vitro fertilization cycle had similar outcomes on the antagonist protocol (CLBR of 14.2%, 95% confidence intervals [CIs]: 13.6%, 14.8%) compared with flare (CLBR of 13.6%, 95% CIs: 12.4%, 14.8%). We evaluated patients undergoing a second cycle after having a poor response (<4 oocytes retrieved) on their first cycle. Patients in the antagonist-to-antagonist group had a similar change in outcomes between the first and second cycles (average CLBR improvement of 13.9%, 95% CIs: 12.1%, 15.6%) compared with the antagonist-to-flare group (average CLBR improvement of 14.4%, 95% CIs: 10.9%, 18.3%). In addition, patients in the flare-to-antagonist group had a similar change in outcomes between the first and second cycles (average CLBR improvement of 10.4%, 95% CIs: 6.6%, 14.5%) compared with the flare-to-flare group (average CLBR improvement of 9.0%, 95% CIs: 5.1%, 13.4%).

Conclusion Poor responders have similar outcomes on an antagonist protocol compared with a flare protocol for both the first and second cycles.