Related Experiment Video
Updated: Mar 18, 2026
Modified MicroSecure Vitrification: A Safe, Simple and Highly Effective Cryopreservation Procedure for Human Blastocysts
Published on: March 2, 2017
Comparison of birth weights in patients randomly assigned to fresh or frozen-thawed embryo transfer
Bruce S Shapiro1, Said T Daneshmand1, Carrie E Bedient1
1Fertility Center of Las Vegas and University of Nevada School of Medicine, Las Vegas, Nevada.
Objective:
To estimate birth weight differences between patients randomized to fresh or thawed ET.
Design:
Post hoc analysis of results from two similar randomized trials.
Setting:
Private fertility center.
Patient(S):
One hundred thirty-four first-time IVF patients, ages 18-40 years at oocyte retrieval, who had live birth.
Intervention(S):
Patients were randomly assigned to have either fresh blastocyst transfer or all bipronuclear oocytes frozen followed by thaw, extended culture, and blastocyst transfer in a subsequent cycle. Preimplantation genetic screening was not allowed.
Main Outcome Measure(S):
Mean birth weight.
Result(S):
After allowing for the contributions of multiple significant variables (gestational age at birth, the presence of a vanished twin, number of infants delivered) in multiple linear regression, the adjusted mean birth weight was 166 g (95% confidence interval, 43-290 g) lower after fresh blastocyst transfer when compared with transfer of blastocysts derived from thawed bipronuclear oocytes.
Conclusion(S):
Birth weights are lower in cycles with fresh blastocyst transfer after controlled ovarian stimulation than in transfers of frozen-thawed embryos in the absence of ovarian stimulation. This finding confirms similar results reported in many retrospective studies.
Clinical Trial Registration Numbers:
NCT00963625 and NCT00963079.
