Related Experiment Video
Updated: Feb 8, 2026

Minimally Invasive Embryo Transfer and Embryo Vitrification at the Optimal Embryo Stage in Rabbit Model
Published on: May 16, 2019
Improved outcomes after blastocyst-stage frozen-thawed embryo transfers compared with cleavage stage: a Society for
Emily C Holden1, Banafsheh N Kashani1, Sara S Morelli2
1Obstetrics, Gynecology and Women's Health, Rutgers-New Jersey Medical School, Newark, New Jersey.
Objective:
To investigate whether there is a difference in obstetrical and perinatal outcomes in blastocyst frozen-thawed embryo transfers (FETs) compared with cleavage-stage FET.
Design:
A retrospective cohort study.
Setting:
Not applicable.
Patient(S):
Women undergoing autologous FETs at either the blastocyst stage (n = 118,572) or the cleavage stage (n = 117,619) reported to the Society for Assisted Reproductive Technology in the years 2004-2013.
Intervention(S):
None.
Main Outcome Measure(S):
Live birth, gestational age, birth weight, miscarriage.
Result(S):
After controlling for confounders, there were a 49% increased odds of live birth after blastocyst-stage FET compared with cleavage-stage FET (odds ratio [OR] = 1.49; 95% confidence interval [CI], 1.44, 1.54). Additionally, blastocyst FET was associated with a 68% (OR = 1.68; 95% CI, 1.63, 1.74) increased odds of clinical pregnancy and an 7% (OR = 0.93; 95% CI, 0.88, 0.92) decreased odds of miscarriage. There was also a 16% increased odds of preterm delivery (OR = 1.16; 95% CI, 1.06, 1.27) after blastocyst FET but no difference in birth weights.
Conclusion(S):
In patients undergoing FET, blastocyst-stage transfer is associated with higher live-birth rates when compared with cleavage-stage transfers. Furthermore, perinatal outcomes are similar between the groups.
Related Concept Videos
Cleavage and Blastulation
Predicting Reaction Outcomes
Outcomes of Glycolysis
Cellular respiration can occur aerobically (with oxygen) or anaerobically (without oxygen). In the presence of oxygen, cellular respiration starts with glycolysis and continues with pyruvate...
Guidelines for Writing Outcome
Patient outcomes reflect the patient's response to the goal rather than what the nurse aims to achieve. Terminology should be observable and measurable to avoid the reader's interpretation. The desired outcome should be realistic and achievable in the designated care timeframe. Expected outcomes should align with adjunctive therapies. The outcome should enhance care...
Stages of Infection
Stages of General Anesthesia

