increasing the number of embryos transferred from two to three, does not increase pregnancy rates in good prognosis patients

background: to compare the pregnancy outcomes after two embryos versus three embryos transfers (ets) in women undergoing in vitro fertilization (ivf)/intracytoplasmic sperm injection (icsi) cycles. materials and methods: this retrospective study was performed on three hundred eighty seven women with primary infertility and with at least one fresh embryo in good quality in order to transfer at each ivf/icsi cycle, from september 2006 to june 2010. patients were categorized into two groups according to the number of et as follows: et2 and et3 groups, indicating two and three embryos were respectively transferred. pregnancy outcomes were compared between et2 and et3 groups. chi square and student t tests were used for data analysis. results: clinical pregnancy and live birth rates were similar between two groups. the rates of multiple pregnancies were 27 and 45.2% in et2 and et3 groups, respectively. the rate of multiple pregnancies in young women was significantly increased when triple instead of double embryos were transferred. logistic regression analysis indicated two significant prognostic variables for live birth that included number and quality of transferred embryos; it means that the chance of live birth following icsi treatment increased 3.2-fold when the embryo with top quality (grade a) was transferred, but the number of et had an inverse relationship with live birth rate; it means that probability of live birth in women with transfer of two embryos was three times greater than those who had three et. conclusion: due to the difficulty of implementation of the elective single-et technique in some infertility centers in the world, we suggest transfer of double instead of triple embryos when at least one good quality embryo is available for transfer in women aged 39 years or younger. however, to reduce the rate of multiple pregnancies, it is recommended to consider the elective single et strategy.