Number of supernumerary vitrified blastocysts is positively correlated with implantation and live birth in single-blastocyst embryo transfers.

Objective: To estimate whether live birth in single-blastocyst transfers is correlated with the number of sibling supernumerary vitrified blastocysts (embryos not transferred) generated from that same cycle.

Design: Retrospective cohort study.

Setting: A large academic assisted reproduction clinic.

Patient(s): All single-blastocyst transfers in 2010 graded as "good" embryos by Society for Assisted Reproductive Technologies (SART) criteria.

Intervention(s): None.

Main Outcome Measure(s): Implantation and live birth.

Result(s): Of the 655 single-blastocyst transfers that met inclusion criteria, implantation occurred in 65% and live birth in 54% of cycles. In chi-square analysis, patients with supernumerary vitrified blastocysts had a statistically higher implantation rate (65% versus 50%) and live-birth rate (56% versus 41%) when compared with patients without supernumerary blastocysts. Univariate logistic regression demonstrated an increase in implantation (OR 1.09; 95% CI, 1.03-1.15) and live birth (OR 1.06; 95% CI, 1.02-1.09) with increasing number of supernumerary blastocysts. Multivariate logistic regression analysis demonstrated that patient age and the number of supernumerary blastocysts were statistically significantly associated with implantation and live birth.

Conclusion(s): The number of supernumerary vitrified blastocysts correlated positively with the odds of implantation and live birth in good quality single-blastocyst transfers. Patients with supernumerary blastocysts are good candidates for single-embryo transfer.