Elective single embryo transfer (ESET) versus double embryo transfer (DET) following failed mandatory single embryo transfer (MSET)

Abstract

To compare live birth and multiple birth rates among women who underwent eSET versus DET in the first frozen embryo transfer (FET) cycle following a failed fresh mSET. Retrospective cohort study. All patients at our institution from 1/1/2012-9/14/2017 who met criteria for mSET (age <38, good quality blastocyst, and no previous failed fresh cycle), did not have a live birth following their first fresh transfer, had at least 2 remaining cryopreserved blastocysts, and subsequently underwent FET were included. Primary outcomes were live birth per transfer and multiple birth per delivery. Secondary outcomes were clinical pregnancy rate, miscarriage rate, ectopic pregnancy rate, term vs. preterm delivery, vaginal delivery vs. cesarean section, and infant birth weight. Exclusion criteria were preimplantation genetic testing (PGT) cycles, FET cycles in which only 1 embryo survived the thaw process, mSET due to maternal condition (e.g. unicornuate uterus), cycles in which birth data were not available, and donor oocyte cycles. Chi-squared tests and t-tests were used to compare demographic, cycle characteristics, and outcome data between groups. Medians with interquartile ranges, means with standard deviation, or percentages are presented. Of the 731 patients who underwent an initial mSET and had outcome data available, 450 had a live birth (61.5%). Of the 281 that failed their fresh mSET, 218 of these went on to have a FET within our time frame (77.6%). Of those, 54 patients were excluded due to no outcome data available (n=9), <2 blastocysts frozen (n=15), only 1 surviving embryo available to transfer after warming (n=27), or mSET due to maternal condition (n=3). This left 164 patients, of which 88 (53.7%) chose to transfer 1 embryo and 76 (46.3%) chose to transfer 2 embryos in their FET. Demographic and cycle characteristics were similar between eSET and DET patients (Table 1). DET patients had a significantly higher live birth rate and clinical pregnancy rate than eSET patients. However, DET patients also had a significantly higher multiple birth rate, C-section rate, and lower birth weight (Table 1). There was no other differences in outcomes seen between groups. In a group of good prognosis patients with an unsuccessful mandatory single embryo transfer, DET in the subsequent cycle resulted in a higher live birth rate than SET, but also was associated with a much higher multiple birth rate. When deciding on the number of embryos to transfer in this group, patients and providers should consider both the higher pregnancy rate and the significant risk of multiples with DET vs. SET.Tabled 1Demographic and Cycle CharacteristicsceSET (n=88)DET (n=76)pAge31 (29-34)32 (29-34)0.248BMI26.7 (21.9-31.5)25.4 (22.6-32.7)0.618Number of oocytes retreived18 (13-25)18 (13-30)0.377Number of blastocysts cryopreserved3 (2-6)4 (2-7)0.345Parity0 (0-0)0 (0-1)0.586Live birth39 (44.3%)52 (68.4%)0.002Multiple birth1 (2.6%)19 (35.8%)<0.001Clinical pregnancy53 (60.2%)57 (75.0%)0.045Preterm delivery5 (12.8%)13 (25.0%)0.149C-section13 (33.3%)29 (55.8%)0.034Birth weight (grams)3540 (3090-3720)3090 (2584-3443)0.003 Open table in a new tab