Table 1.
Characteristics of treatment cycles performed during the study period
| Characteristic | 2004/2005 (n = 1198) | 2006/2007 (n = 1253) | Difference (95% CI) | P value |
|---|---|---|---|---|
| Age (years) | 35.2 (4.5) | 35.8 (4.4) | −0.59 (−0.94 to −.0.24) | 0.001 |
| IVF cycle order | 1.7 (1.0) | 1.7 (1.1) | 0.016 (−0.1 to 0.069) | 0.71 |
| Basal FSH level (iu/l) | 6.5 (2.4) | 7.3 (2.7) | −0.82 (−1.03 to −0.62) | 0.0001 |
| Basal estradiol level (pmol/l) | 173 (159) | 169 (110) | 4.1 (−7.4 to 15.6) | 0.49 |
| Duration of stimulation, days | 10.1 (1.7) | 10.4 (1.9) | −0.29 (−0.43 to −0.15) | 0.0001 |
| Daily dose of FSH (iu) | 281 (105) | 281 (101) | 0.24 (−7.9 to 8.4) | 0.95 |
| Number of oocytes collected | 10.3 (6.6) | 11.2 (7.4) | −0.84 (−1.4 to −0.27) | 0.004 |
| Cycles reaching ET (%) | 83 | 87 | 0.004 | |
| Day 5 selective SBT (%) | –– | 9 | <0.0001 | |
| Number of embryos replaced per transfer | 1.9 (0.4) | 1.8 (0.5) | 0.07 (0.03 to 0.11) | 0.0002 |
| Cycles achieving freezing (%) | 22 | 28 | <0.001 | |
| Pregnancy rate/cycle (%) | 33 | 38 | 0.013 | |
| CPR/cycle (%) | 27 | 32 | 0.015 | |
| Implantation rate (%) | 25 | 28 | 0.11 | |
| MPR (%) | 32 | 17 | <0.001 |
ET, embryo transfer; FSH, follicle-stimulating hormone; SBT, single blastocyst transfer.
Values are expressed as mean (SD) unless indicated otherwise.