Blastocyst-stage superior to cleavage-stage embryo transfer
Source: Human Reproduction 2007; Advance online publication
Exploring the live birth rates after transfer of equal number of blastocyst or cleavage-stage embryos in IVF.
MedWire News: Women receiving IVF have a greater chance of a live birth if their embryos are transferred at the blastocyst, rather than the cleavage, stage, a review of the current literature suggests.
The researchers note that their findings were dependent on an equal number of embryos being transferred with each method.
Evangelos Papnikolaou and colleagues from Free University of Brussels inBelgium extensively search the medical literature and identified eight randomized controlled trials that met their inclusion criteria. A total of 165 patients were reviewed.
Patients who had a blastocyst-stage compared with a cleavage-stage embryo transfer were 1.39 times more likely to have a live birth.
The probability of clinical pregnancy was also higher with blastocyst-stage transfer, while the risk for multiple pregnancies was similar between the two types of transfer.
The researchers note that the cancellation rate was significantly higher in the group of patients undergoing blastocyst-stage embryo transfer. Although cancellation can be devastating for the patient, the researchers note that it avoids offering false hope.
Finally, the cryopreservation rate was significantly lower with blastocyst-stage compared with cleavage-stage embryo transfer.
"The current meta-analysis suggests that... the probability of both live birth and clinical pregnancy is significantly higher when performing the embryo transfer at the blastocyst stage than the cleavage stage," Papnikolaou et al conclude.