Elective Single Cleavage-Stage Embryo Transfer in IVF Patients with Suboptimal Ovarian Response is Not Detrimental to Cumulative Pregnancy and Reduces Multiple Pregnancy Rates.

Purpose: To evaluate whether elective single embryo transfer in patients with suboptimal response to ovarian stimulation is detrimental to pregnancy rates compared to double embryo transfer.

Methods: A case-control retrospective study was performed in a cohort of couples undergoing IVF at the Infertility Unit of the ASST Lariana with ≤ 9 oocytes and at least 2 viable embryos. A total of 424 women were analyzed in the "double embryo transfer" group (n = 212) and elective "single embryo transfer" group (n = 212); they were matched 1:1 for female age, ovarian reserve and number of previous cycles. Cumulative clinical pregnancy rate per oocyte retrieval was the main outcome.

Results: The cumulative pregnancy rate per cycle, including the fresh embryo and subsequent frozen embryo transfers, was 26% and 26%, respectively. Considering the main confounding factors, a binomial logistic model indicated that the cumulative clinical pregnancy rate was not significantly affected when a single embryo transfer was performed in women recovering up to nine oocytes.

Conclusion: Live birth rate was similar between the two groups, while twin pregnancies were significantly reduced in women receiving single embryo transfer suggesting that elective single embryo transfer in patients with a limited number of embryos is not detrimental to pregnancy rates.