Clinical and ongoing pregnancy rates are improved by the addition of letrozole in the hormone replacement cycles undergoing the frozen-thawed single blastocyst transfer

Abstract

pregnancy is defined by ultrasonographic demonstration of fetal cardiac activity. Implantation rate is defined as total gestational sacs divided by total embryos transferred in each category. CONCLUSION: These data suggest that extended embryo culture to day 5 does not adversely affect embryo efficiency in a select group of women with only 6 zygotes and does not pose a detrimental effect on cumulative live birth rate. Additionally, a significant decrease in cumulative twin delivery rate is achieved by this strategy if single embryo transfer is used frequently for day 5 ETs. This may translate to a safer IVF practice strategy in prevention of multiple pregnancies, including twins.