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The effect of embryo quality on subsequent pregnancy rates after in vitro fertilization
M Erenus1, C Zouves, P Rajamahendran
1Department of Obstetrics and Gynaecology, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Objective:
To determine if a simple morphological classification of embryos was predictive of subsequent pregnancy.
Design:
Prospective case series.
Setting:
University-based in vitro fertilization (IVF) program.
Patients, Participants:
Consecutive embryo transfer (ET) cycles (n = 206).
Interventions:
Embryos were classified into three grades: (1) equal-size blastomeres with no fragmentation; (2) unequal-size blastomeres; and (3) evidence of fragmentation.
Main Outcome Measures:
Embryo quality, age, indication for IVF, and stimulation protocol were evaluated for their effect on pregnancy rates (PR's).
Results:
In cycles in which the best embryo transferred was grade 3, 2, or 1, the clinical PRs per ET were 0% (0/11 cycles), 12.8% (6/47 cycles, P less than 0.05), and 21.8% (32/148 cycles, P less than 0.05), respectively. When one, two, or three or more grade 1 embryos were replaced, the clinical PRs per ET were 15.6%, 16.3%, and 40% (P less than 0.05), respectively. Using logistic regression, embryo quality (P = 0.0011) and patient's age (P = 0.0044) were the only variables that affected PRs.
Conclusion:
The transfer of more than two good quality embryos had a positive effect, patient's age had a negative effect on PRs after IVF-ET.