Table 2.
Comparison between slow freezing and vitrification after embryo thaw and transfer
| Group A (Slow cooling) | Group B (Vitrification) | Significance (P value) a | |
|---|---|---|---|
| Patients (% of fresh cycles) | 48 (35.3%) | 51 (40.4%) | N/A |
| Mean age of thaw cycles | 31.5 ± 2.4 | 32.0 ± 1.6 | 0.86 |
| Number of embryos thawed (mean ± sd/patient, range) | 162 (3.6 ± 2.4, 1–5) | 158 (2.9 ± 1.1, 1–5) | 0.79 |
| Number surviving thaw (%) | 141 (87.0%) | 147 (93.1%) | 0.89 |
| Number of partially lysed embryos | 66 (46.8%) | 25 (17.0%) | 0.00 |
| Average number of blastomeres post-thaw (range) | 5.3 ± 2.1 (1–8) | 7.2 ± 1.1 (5–8) | 0.0001 |
| Number of transfers | 48 | 51 | N/A |
| Number of transferred embryos (Mean ± sd, range) | 141 (2.9 ± 1.6, 1–5) | 147 (2.9 ± 1.1, 1–5) | 1.0 |
| Number of clinical pregnancies (% pregnancies/transfer) | 17 (35.4%) | 18 (35.3%) | 0.16 |
| Number of fhb’sb (Implantation rate) | 19 (13.5%) | 21 (14.3%) | 0.23 |
| Pregnancies to term | 17 | 17 | N/A |
| Liveborn babies (% embryos implanted) | 17 (89.5%) | 19 (90.5%) | N/A |
| Mean gestational age at birth (weeks) | 37.0 ± 1.0 | 37.3 ± 1.0 |
Data is presented as actual figures. Percentages are presented in parentheses where necessary. Mean ± sd is presented where necessary. Significance is calculated with Students t-test for means ± sd or 2-tailed z-test to examine the differences between proportions. aP-values < 0.05 are considered significant. bFoetal heart beats. N/A—not applicable