Blastocyst versus cleavage stage transfer in in vitro fertilization: differences in neonatal outcome?
OBJECTIVE
To compare neonatal outcome of blastocyst and cleavage stage embryo transfers after IVF.


METHODS
Register study.


METHODS
Births recorded in the Swedish Medical Birth Register after IVF performed, 2002-2006.


METHODS
Treatments reported from all Swedish IVF clinics.


METHODS
None.


METHODS
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).


RESULTS
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.


CONCLUSIONS
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.
Källén
Bengt
B
Tornblad Institute, University of Lund, Lund, Sweden. Bengt.Kallen@med.lu.se
Finnström
Orvar
O
Lindam
Anna
A
Nilsson
Emma
E
Nygren
Karl-Gösta
KG
Olausson
Petra Otterblad
PO
D000328:Adult; D001034:Apgar Score; D001757:Blastomeres / Q000502:physiology*; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D000013:Congenital Abnormalities / Q000453:epidemiology; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008297:Male; D017063:Outcome Assessment, Health Care; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013548:Sweden