Pregnancy rates (prs) per cycle similar for the first four transfers despite improved prs

Abstract

A study was performed to use life-table analysis to evaluate the cumulative probability of pregnancy following ET and to determine whether there is any decrease in PRs for the first four ETs now that PRs with IVF have improved so much. The study presented here evaluated the first four cycles of ET in our IVF center from 1/1/97 through 6/30/98. Since PRs/ET are equal in our center regardless of whether they are fresh or frozen, the first four ETs were assessed regardless of whether they were cryopreserved-thawed. All patients were evaluated, including women with elevated baseline serum FSH levels, previous poor responders, or patients with failed IVF cycles in other centers. Oocyte recipients, gestational carriers, and women receiving donor embryos were excluded. The patients were stratified into four age groups. The mean number of oocytes retrieved significantly decreased with advancing age20.4 for <30, 17.8 for 30–34, 12.7 for 35–39, and 7.5 for 40–44. Fertilization rates were similar. The respective number of embryos formed also significantly decreased with advancing age: 12.3, 10.9, 8.0, and 4.7. The mean number of embryos transferred in each age group was 3.0, 3.1, 3.1, and 3.5. For group 1, the probability of clinical pregnancy per transfer for the four cycles was 0.45, 0.49, 0.44, and 0.50 and the cumulative probability rates were 0.45, 0.72, 0.84, and 0.92. These rates were 0.40, 0.45, 0.40, and 0.33 and 0.40, 0.67, 0.80, and 0.87 in group 2, 0.40, 0.36, 0.29, and 0.38 and 0.40, 0.62, 0.73, and 0.83 in group 3, and 0.17, 0.27, 0.32, 0.23 and 0.17, 0.40, 0.59, and 0.68 in group 4. The probability of viable pregnancy per transfer was also similar in all four cycles in all four groups, and the cumulative probability of viable pregnancy after four cycles was 0.88, 0.82, 0.69, and 0.52 for the four groups. The majority of first cycle transfers were not frozen—31.0%, 30.3%, 20.5%, and 20.4%—but thereafter represented the majority of transfers for the three younger groups (ranging from 68.6% to 88.9%) and was 49.2%, 72.0%, and 38.4% for group 4. Thus, despite improved PRs per transfer, no other interventions seem necessary for at least the first four transfers.