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

Abstract

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. 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. 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. 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.