Birthweight of singletons born after cleavage-stage or blastocyst transfer in fresh and warming cycles

AbstractSTUDY QUESTIONDoes extended culture to the blastocyst stage affect singleton birthweight after either fresh or vitrified-warmed embryo transfer?SUMMARY ANSWERSingleton birthweightz-scores did not vary significantly after a fresh blastocyst transfer, whereas the additional effect of vitrification remains inconclusive.WHAT IS KNOWN ALREADYObservational studies have associated extended culture with an increased risk of preterm birth and low birthweight. On the contrary, in terms of birthweight and gestational age, singletons born after vitrification have been associated with a better perinatal outcome when compared to those born following a fresh transfer.STUDY DESIGN, SIZE, DURATIONOur post-hoc cohort analysis on neonatal outcomes included 447 liveborn singletons was derived from a recent retrospective analysis on cumulative live birth rates after cleavage-stage and blastocyst transfers. These babies were born following a fresh single cleavage-stage transfer (FCT Day 3,n = 113), fresh single blastocyst transfer (FBT Day 5,n = 218), vitrified-warmed cleavage-stage transfer (VCT Day 3,n = 58) or vitrified-warmed blastocyst transfer (VBT Day 5,n = 58).PARTICIPANTS/MATERIALS, SETTING, METHODSSingleton birthweight was the primary outcome measure. Gestational age and gender of the newborn were accounted for by using birthweightz-scores in a multivariable linear regression analysis, adjusting for other confounders (maternal age, BMI, parity and smoking behaviour). Vanishing tw...
Source: Human Reproduction - Category: Reproduction Medicine Source Type: research