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.