Aim:To compare the clinical outcomes of cryopreservedthawed embryo transfer among patients with a normal menstrual cycle who had natural or hormone-replacement cycles. Results: Cryopreserved-thawed embryo transfer in patients who had a natural or hormone-replacement cycle resulted in clinical pregnancy in 43.1% and 40.4%, respectively; a rate of miscarriage of 14.5% and 23.6%, respectively; and a rate of ongoing pregnancy and delivery of 36.5% and 30.9%, respectively. None of these differences were statistically significant. Methods: Conclusions:Patients with a normal menstrual cycle who have natural or hormone-replacement cycles can be expected to have comparable clinical outcomes with cryopreserved-thawed embryo transfer. (Reprod Med Biol 2007; 6: 53-57)

Purpose In assisted reproductive technology, normal zygotes are bipronuclear (2PN) during fertilization confirmation; however, sometimes, nonpronuclear zygotes (0PN) and monopronuclear zygotes (1PN) are found during routine observations. Methods To elucidate the clinical usefulness of in vitro‐fertilized embryos, we investigated the rates of clinical pregnancy, live birth, miscarriage, and congenital abnormality after transfer of frozen‐thawed 1PN‐ and 0PN‐derived single blastocysts at Denentoshi Ladies Clinic, Kanagawa, Japan. Results The rates of pregnancy and live birth for 1PN‐derived blastocysts obtained by conventional in vitro fertilization were 37.5% and 27.1%, respectively, which was not significantly different from those for 2PN‐derived blastocysts; however, the rates for 0PN‐derived blastocysts were significantly lower. The pregnancy and live birth rates for 0PN‐derived embryos obtained by intracytoplasmic sperm injection (ICSI) were 45.7% and 34.8%, respectively, which was not significantly different from those for 2PN‐derived blastocysts; however, the rates for 1PN‐derived blastocysts were significantly lower (4.0% for both) than those for 2PN‐ and 0PN‐derived blastocysts. No congenital abnormalities were found in infants resulting from transfer of 0PN‐ or 1PN‐derived blastocysts. Conclusions Both 1PN‐ and 0PN‐derived blastocysts can be used for embryo transfer; however, care should be taken in making decisions about 1PN‐derived blastocysts, especially if they are obtained by ICSI.

Purpose As age increases, oxidative stress increases, sperm motility decreases, and DNA fragmentation increases. To date, reports of age-related effects on semen have focused on reactive oxygen species (ROS) or total antioxidant capacity (TAC) as indicators of oxidative stress. However, assessments of ROS and TAC must be considered within a more comprehensive context in order to correctly evaluate oxidative stress and interpret findings. In this regard, the purpose of this study was to investigate the relationship between the static oxidation reduction potential (sORP) and paternal age with the goal of using the sORP as an indicator of semen oxidative stress. Materials and Methods Semen samples from 173 men were analyzed for the following parameters: volume, motility, and beat cross frequency (BCF). The sORP was measured by using the MiOXSYS™ system. The correlation between semen parameters and the sORP level was analyzed as a function of age. The rate of sORP positivity was compared between men <34 and ≥34 years of age, with a positive sORP defined as a level ≥1.38. Results Volume, motility, and BCF were negatively correlated with age (p<0.001). The semen sORP level was positively correlated with age (p<0.05). The rate of sORP positivity was significantly increased in men ≥34 years of age compared with that in men <34 years of age (33% compared with 12%, respectively; p<0.01). Conclusions The sORP may play a role in age-related decreases in semen parameters (volume, motility, and BCF). The rate of sORP positivity increased significantly after 34 years of age.

Blastocysts are reportedly suitable for preventing multiple pregnancies as a result of the high implantation rate per embryo. The present study compared clinical results for elective single embryo transfer (ET) between blastocysts and cleavage-stage embryos in order to ascertain the usefulness of blastocyst culturing in single ET. Between January 2002 and December 2004, conventional fertilization ET and/or intracytoplasmic sperm injection was carried out for single ET in 86 cycles, to prevent multiple pregnancies (for medical reasons or because of patient wishes). Among the 80 cycles in which a fresh embryo was transferred, pregnancy/implantation rates per ET were 35.3% for day 2/3 ET and 50.0% for day 5 ET, and pregnancy/implantation rates per oocyte retrieval were 35.3% for day 2/3 ET and 44.2% for day 5 ET. Ongoing pregnancy/delivery rates per oocyte retrieval were 32.4% for day 2/3 ET and 38.5% for day 5 ET. Monozygotic twinning occurred in one case of day 5 ET. Pregnancy rates per single ET tended to be higher for day 5 ET than for day 2/3 ET. However, no marked differences were identified in ongoing pregnancy/delivery rates per oocyte retrieval between groups. (Reprod Med Biol 2005;: 197-201).