Table 2.
Comparison of outcomes of vitrified-warmed cleavage-stage embryo transfers between the quarter of zona pellucida thinning and the half of zona pellucida thinning groups
| Parameter | quarter (n = 60) | half (n = 60) | P-value |
|---|---|---|---|
| No. of embryos warmed | 104 | 107 | – |
| No. of day 2/day 3 embryos warmed | 48/56 | 54/53 | NS |
| No. of good quality embryos warmed | 65 | 61 | NS |
| No. of good quality day 2/day 3 embryos warmed | 28/37 | 27/34 | NS |
| No. of embryos survived (%) | 99 (95.2) | 103 (96.3) | NS |
| Survival classification | |||
| Fully intact (%) | 95 (91.3) | 97 (90.7) | NS |
| Partially damaged (%) | 4 (3.9) | 6 (5.6) | NS |
| Degenerated (%) | 5 (4.8) | 4 (3.7) | NS |
| Mean no. of embryos transferred ± SD | 1.7 ± 0.5 | 1.7 ± 0.6 | NS |
| Mean zona pellucida thickness ± SD (μm) | 18.7 ± 0.5 | 18.8 ± 0.6 | NS |
| No. of clinical pregnancies (%) | 15 (25.0) | 28 (46.7) | 0.0218 |
| No. of embryos implanted (%) | 16 (16.2) | 33 (32.0) | 0.0090 |
| No. of twin pregnancies (%) | 1 (6.7) | 5 (17.9) | NS |
| No. of miscarriages (%) | 2 (13.3) | 3 (10.7) | NS |
NS not significant. Good quality embryos were defined as those having regular blastomeres, <20% fragments and no multinucleated blastomeres and those containing at least three cells on day 2 or six cells on day 3. Survival classification: Fully intact = 100% cells morphologically intact, Partially damaged = ≥50% cells morphologically intact, Degenerated = <50% cells morphologically intact