Is transferring a lower-quality embryo with a good-quality blastocyst detrimental to the likelihood of live birth?

Objective To determine if transferring a lower-quality embryo with a good-quality blastocyst is detrimental, given that evidence suggests that embryos can signal the endometrium and that embryo quality may affect negatively endometrial receptivity. Design Retrospective cohort study. Setting In vitro fertilization center. Intervention(s) Single- versus double-embryo transfer. Patient(s) Patients with a double-embryo transfer of a good-quality blastocyst plus a lower-quality blastocyst, early blastocyst, or morula were compared with patients receiving a single good-quality blastocyst. Main Outcome Measure(s) Live birth, multiple gestation. Result(s) In this study, 4,640 in vitro fertilization cycles were analyzed. In none of the analyses did transferring a second lower-quality embryo negatively affect birth rate. In the primary analysis, transferring a second lower-quality embryo increased live birth by 10% and the multiple birth rate by 15%. The addition of a fair- or poor-quality blastocyst or early blastocyst markedly increased the twin birth rate by 22%–27% with an 8%–12% increase in live birth. The addition of a morula did not increase live birth but resulted in 12% more multiples. In women younger than 38 years, adding a lower-quality embryo increased the birth rate by 7% but resulted in 18% increase in multiples. In women 38 years or older, adding a lower-quality embryo increased the live birth rate by 9% with a 15% increase in multiples. Conclusion(s) Addition of a lower-quality embryo does not have a detrimental effect on a good-quality blastocyst and results in a small increase in live births. However, this is at the expense of a marked increase in the likelihood of multiple gestations.