Comparison of perinatal outcomes following blastocyst and cleavage-stage embryo transfer: analysis of 10 years’ data from a single centre

Research question: Are there greater risks of adverse perinatal outcomes, in particular of congenital malformations, after blastocyst transfer compared with cleavage-stage embryo transfer in IVF? Design: This was a retrospective cohort analysis from a centre for assisted reproduction at a public hospital in China over the period 2006–2015. The analysis covered all women who conceived (15,254)and newborns (16,213)from IVF/intracytoplasmic sperm injection (ICSI)cycles with cleavage-stage embryo transfer or blastocyst transfer. The principal outcome measures were congenital malformations, preterm birth (PTB), low birthweight (LBW), small for gestational age (SGA)and large for gestational age (LGA). Results: Logistic regression analysis showed that the sex ratio was imbalanced towards male neonates after blastocyst transfer (P=0.001; adjusted OR 1.17, 95%CI 1.07–1.30)but there were no differences in rates of miscarriage, ectopic pregnancy, stillbirth, very preterm birth (<32 weeks), PTB (<37 weeks), LBW, SGA or LGA between blastocyst transfer and cleavage-stage embryo transfer. A total of 176 congenital malformations (123 cleavage-stage embryos versus 53 blastocysts)were identified both in newborns and aborted fetuses, but the difference between groups was not statistically significant. Conclusions: There was no difference in the risks of adverse perinatal outcomes, and in particular of congenital malformation, after blastocyst transfer compared with cleavage-stage transfer, although there was a sex ratio imbalance towards male neonates after blastocyst transfer.