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Updated: Oct 21, 2026
Human Blastocyst Biopsy and Vitrification
Published on: July 26, 2019
Strategy-Based Comparison of Fresh Double Embryo Transfer Versus Sequential Single Embryo Transfers in Women With
Tzu Hsiang Weng1, Chia-Chen Lee1, Kuan-Sheng Lee1
1Division of Reproduction and Infertility, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, MacKay Memorial Hospital, New Taipei 251, Taiwan.
Objective:
To compare the cumulative reproductive outcomes of two embryo transfer strategies in women with adequate blastocyst availability: immediate fresh double embryo transfer (DET) and a sequential strategy consisting of fresh single embryo transfer (SET) followed by frozen-thawed SET derived from the same retrieval cohort.
Design:
A retrospective cohort study was conducted at Taipei MacKay Memorial Hospital using clinical data from January 2017 to December 2023.
Setting:
A single tertiary reproductive center.
Subjects:
Women younger than 40 years with normal ovarian reserve and ≥ two good-quality blastocysts obtained from a single stimulation cycle.
Exposure:
Patients underwent either fresh DET or sequential SET that included a second transfer within three years.
Main Outcome Measures:
Cumulative clinical pregnancy rate (CCPR) and cumulative live birth rate (CLBR) per retrieval cycle.
Results:
A total of 256 patients were included: 135 in the sequential SET group (33.39 ± 3.13 years) and 121 in the fresh DET group (35.41 ± 2.87 years). The CCPR was significantly higher in the sequential SET group than in the fresh DET group (86.7% vs.61.2%; RR: 1.42, 95% CI: 1.21-1.66), as was the CLBR (63.7% vs.51.2%; RR: 1.24, 95% CI: 1.00-1.54). Although the initial pregnancy rate was lower in the group who would have sequential SET than fresh DET (41.4% vs.61.2%), cumulative pregnancy outcomes improved substantially after the second transfer in the SET cohort. The miscarriage rate did not differ significantly between the sequential SET and fresh DET groups (24.7% vs. 14.9%; RR: 1.67, 95% CI: 0.89-3.13), whereas the twin pregnancy rate was markedly lower (0% vs.14.9%, p < 0.001) in the sequential SET group. Based on pooled neonatal data irrespective of plurality, mean gestational age (38.47 vs.37.41 weeks, p = 0.69) and mean birth weight (3065 vs.2773 g, p = 0.09) were comparable between groups. Preterm births per oocyte retrieval cycle were significantly less frequent following sequential SET than fresh DET (2 vs.16, p < 0.001).
Conclusions:
Among patients with favorable embryo availability, sequential SET demonstrated higher cumulative reproductive outcomes within a strategy-based framework than fresh DET. These findings reflect differences in embryo utilization pathways rather than in isolated transfer efficacy; they should be interpreted in the context of treatment continuation and cohort selection.
