Increased male live-birth rates after blastocyst-stage frozen-thawed embryo transfers compared with cleavage-stage: a SART registry study

Abstract Objective To investigate whether there is a difference in live-birth gender rates for blastocyst-stage FETs compared with cleavage-stage FETs. Design Retrospective cohort study. Setting Academic medical center. Patients All women with recorded live births who underwent FET at either the blastocyst-stage or the cleavage-stage, reported to the Society for Assisted Reproductive Technology during 2004-2013 Interventions None. Main outcome measures The primary outcome was live-birth gender rates. Demographic criteria were also collected. Chi-square analyses were used for bivariate associations and multiple logistic regression models were used for adjusted associations, with all two-sided p Result(s) There was a statistically significant increase in the number of live male births following a blastocyst-stage FET compared with cleavage-stage (51.9% vs. 50.5%; p Conclusion(s) In patients undergoing FETs, blastocyst-stage transfers are associated with higher male gender live-birth rates when compared with cleavage-stage.