One plus one is better than two. The best choice for embryo transfer: A
retrospective cohort study
Abstract
Objective: To assess the freeze-only strategy associated with
frozen-thawed single-embryo transfers (SETs) efficiency in
high-responder patients. Design: Retrospective cohort study Setting:
Private reproductive medicine center. Population: A total of 500 IVF
cycles with freeze-all embryos followed by elective frozen-thawed embryo
transfers (eFET). Method: Elective double-embryo transfer (eDET) group
with 291 cycles, in which two embryos were placed in the first eFET, and
elective-SET (eSET) group with 209 cycles, in which the patients
underwent eSET in their first eFET. For those who did not become
pregnant, a second SET was performed (n=60). Main outcome measures: The
ongoing pregnancy rate (PR) was compared after the first FET, and
cumulative ongoing PR was evaluated for the SET group considering
patients who had a second frozen-thawed SET (eSET + SET). Results: No
significant differences were observed in the ongoing PR after the first
FET (eDET: 37.8% versus eSET: 34.8%, p = 0.497). The estimated
cumulative ongoing PR for eSET + SET (52.1%) was significantly higher
than eDET (37.8%, p < 0.001). The linear multiple regression
confirmed that transfer of two embryos in sequential SETs led to a
higher chance of implantation than did the transfer of two embryos
together (eDET; coefficient: 0.142, p < 0.001). The eDET group
had 26.9% twin pregnancies compared with 1.9% in the eSET (p
< 0.001). Conclusions: Sequential SETs in freeze-only cycles
may be the best option to attain high success rates in high-responder
patients, leading to an increased chance of implantation and avoidance
of multiple gestations.