H.J. Yoon

Pregnancies Resulting from In Vitro Matured Oocytes Collected from Women with Regular Menstrual Cycle

Purpose: To demonstrate that human immature oocytes retrieved from women with regular menstrual cycles can undergo maturation and fertilization, and that the resulting embryos can establish pregnancies.Methods: Immature oocytes (n = 568) were retrieved from women with regular menstrual cycle. The intact immature oocytes (n = 506) were allowed to mature in YS medium supplemented with 70% human follicular fluid (hFF); the matured oocytes were fertilized with husband sperm. Two pronuclei oocytes were cocultured with cumulus cells in YS medium supplemented with 10% hFF until 2 or 3 days after insemination. The cleaved embryos were transferred in uteri.Results: Follicles were aspirated on Day 9.2 ± 5.3 of 63 natural cycles from 51 patients (mean age = 34.8 ± 4.0 years). The average number of retrieved immature oocytes was 9.0. The maturation rate was 74.3% (376/506). The two PN and cleavage rates were 72.6% (273/376) and 89.0% (243/273), respectively. Embryo transfer was achieved in 51 cycles and clinical pregnancy rate was 17.6% (9/51).Conclusions: The results suggest that in vitro matured oocytes can undergo fertilization and the resulting embryos may successfully lead to pregnancies. However, further research is needed to improve IVM technique to achieve success rate comparable to gonadotrophin stimulated cycles.

Alternative embryo transfer on day 3 or day 5 for reducing the risk of multiple gestations

Purpose: This study was carried out to reduce the possibility of high-order multiple gestations and the failure of embryo transfer by determining their replacement date based on the number and quality of 2-day embryos.Methods: All zygotes were cocultured with cumulus cells in 10 μl of YS medium containing 10% human follicular fluid (hFF) for 48 or 96 hr. In period I, all embryos were transferred on day 3 (1032 cycles). In period II, the embryos were transferred on either day 3 or day 5 by determining their replacement date based on the number and quality of 2-day embryos: there were 2701 patients in whom embryos were replaced on day 3 (in the case that the number of zygotes was less than eight and the number of good-quality embryos was less than three) and 1952 patients less than 40 years old in whom embryos were replaced on day 5 (in the case that the number of zygotes was eight or more and/or the number of good-quality embryos was three or more). On the other hand, patients who were 40 years old or more were alloted to day 3 transfer cycles, regardless of the number and quality of the 2-day embryos, due to the possibility of their not producing blastocyst-stage embryos in vitro.Results: The number of embryos transferred in period II was 2.9 ± 0.6, while that in period I was 3.7 ± 0.5. The multiple pregnancy rate was significantly decreased in period II (30.7%) compared to that (49.6%) in period I, while the pregnancy and implantation rates in period II (36.1 and 16.4%, respectively) were not lower than those (34.9 and 16.1%, respectively) in period I. The rate of triplet or more gestations was significantly minimized in period II (2.3%) compared to that in period I (26.5%).Conclusions: We propose that determination of the date on which embryos should be transferred based on the number and quality of embryos on day 2 may help to maintain an acceptable pregnancy rate, while minimizing embryo transfer failure and high-order multiple gestations.

High implantation and pregnancy rates with transfer of human hatching day 6 blastocysts

Although improved outcomes of IVF after transfer of blastocysts has been reported (1, 2), it remains uncertain which blastocyst can develop into a viable fetus. At present, expansion of the blastocyst is the most practical selection criterion. However, if extended culture of embryos produces many expanded-stage blastocysts, it is not easy to decide which blastocysts to transfer (Fig. 1 A). In addition, some blastocysts fail to hatch out of the zona, despite evidence that the blastocoelic cavity had expanded and the zona pellucida had thinned (3).