Blastocyst versus cleavage stage transfer in in vitro fertilization: differences in neonatal outcome?
Received 13 October 2009; received in revised form 7 December 2009; accepted 7 December 2009. published online 04 February 2010. Corrected Proof
Objective
To compare neonatal outcome of blastocyst and cleavage stage embryo transfers after IVF.
Design
Register study.
Patient(s)
Treatments reported from all Swedish IVF clinics.
Intervention(s)
None.
Setting
Births recorded in the Swedish Medical Birth Register after IVF performed, 2002–2006.
Main Outcome Measure(s)
Some neonatal characteristics were compared in 1,311 infants born after blastocyst-stage transfer and 12,562 infants born after cleavage-stage transfer. Comparisons were also made with all births, 2002–2007 (n = 598,687).
Result(s)
After adjusting for year of birth, maternal age, parity, smoking habits, and body mass index, the risk of preterm birth among singletons was significantly greater after blastocyst-stage transfer than after cleavage-stage transfer. The risk of congenital malformations was also significantly higher. When the analysis was restricted to clinics where blastocyst transfers were made, the risk estimates increased for preterm birth, low birth weight, low APGAR score, and respiratory diagnoses, but did not change for congenital malformations.
Conclusion(s)
The results indicate a small increase in risk associated with blastocyst transfer, perhaps owing to the longer period of in vitro culture. There is a possibility that this effect is due, at least in part, to a selection of women for blastocyst transfers. Further studies are needed either to verify or to refute the found associations.
Supported by a grant from Evy and Gunnar Sandberg Foundation, Lund, Sweden, to B.K.
B.K. has nothing to disclose. O.F. has nothing to disclose. A.L. has nothing to disclose. E.N. has nothing to disclose. K.-G.N. has nothing to disclose. O.P.O. has nothing to disclose.
ABSTRACT