O-292 Does ovulation trigger enhance live birth in a natural cycle for frozen embryo transfer: A randomized controlled trial

Abstract

Abstract Study question Does ovulation trigger enhance pregnancy rate in a natural cycle (NC) for frozen embryo transfer (FET)? Summary answer Pregnancy rates after a FET are similar in a natural cycle with detection of a spontaneous LH surge or with a triggered ovulation. What is known already Several studies have explored whether one approach might appear to be more beneficial in terms of pregnancy or live birth rates, but with inconsistent results. Thus, the best protocol to identify the time of ovulation in NC and to plan the FET is still undefined. Study design, size, duration This was a bicentric, two-arm, randomized, controlled and open-label trial, including 108 patients for 18 months. In the spontaneous-NC group, the LH surge was defined as a rise of the serum LH level at least three times above the basal LH serum value with a serum progesterone level three days after the LH surge above 3 ng/mL. Participants/materials, setting, methods Patients included were aged 18- to 39-year-old, had regular cycles and were planned for an autologous frozen day-5 blastocyst transfer in a NC. They did not have endometriosis stage AFSr 3 nor 4 nor adenomyosis. Fifty-four patients per group were included. In the modified-NC group, a spontaneous LH surge was observed in 16 women before the hCG-trigger could be administrated: they were re-allocated to the spontaneous-NC for the per-protocol (PP) analysis. Main results and the role of chance Patients characteristics were comparable in both groups. Pregnancy rates were similar in the spontaneous-NC and the modified-NC group in the intention-to-treat (ITT) (41.3 versus 37.8% respectively, p = 0.85) and in the PP analysis (39.3% versus 40% respectively, p = 0.9). Ongoing pregnancy, miscarriage and live birth rates were also similar. Significantly more visits were needed in the spontaneous-NC (3.4 ± 0.81 versus 2.59 ± 1.0, p < 0.0001 in the ITT analysis and 3.18 ± 0.93 versus 2.63 ± 1.03, p = 0.0064 in the PP analysis). Limitations, reasons for caution Due to group redistribution (spontaneous LH surge before hCG trigger), the number of subjects in the modified-NC group is low for the PP analysis. This may reduce the power of the trial which may fail to detect a small difference. Wider implications of the findings The results reinforce previous data that showed similar efficacy of the s-NC and the m-NC. This allows the patient to choose from several options depending on her preference. Trial registration number NCT03428165