[Effect of oxygen concentration on outcome of in-vitro fertilization-embryo transfer].

OBJECTIVE: To investigate the effect of low and high oxygen concentration on embryo development, pregnancy outcome and birth defects of in vitro fertilization-embryo transfer (IVF-ET). METHODS: According to the oxygen concentration of in vitro culture environment, the IVF-ET performed in the Women's Hospital, Zhejiang University School of Medicine during 2013 and 2015 were divided into low oxygen concentration group (n=2036, 5% O2) and high oxygen concentration group (n=4617, 20% O2). The rate of fertilization, good quality embryo, clinical pregnancy, ectopic pregnancy, abortion and birth defect were compared between two groups. RESULTS: The good quality embryo rate was significantly higher in the low oxygen concentration group (P<0.05). However, no significant differences were found between two groups in the rate of fertilization, clinical pregnancy, ectopic pregnancy, abortion and birth defect (all P>0.05). CONCLUSIONS: Low oxygen environment may improve the potential of embryonic development, but its impact on pregnancy outcome and birth defect is not significant.

Clinical evaluation of two formulations of slow-freezing solutions for cleavage stage embryos.

PURPOSE: The aim was to investigate if improved survival rates could be achieved using a new formulation of solutions for slow freezing of human cleavage stage embryos. METHODS: The evaluation was divided into two parts. The first part was a retrospective analysis of results obtained after freezing and thawing of day 3 embryos from 400 women using an old formulation of cryopreservation solutions compared to results from 108 women for which cryopreservation had been performed using new compositions of solutions. The second part was prospective, adding cycles until similar numbers of patients had been included in both groups. In total, 2274 embryos from 897 patients were thawed using the old formulation of solutions while 1273 embryos from 542 patients were frozen and thawed using the new solutions. The primary endpoint was survival rate. RESULTS: With the new solutions, the survival rate increased from 82.1 to 94.4 % and the complete embryo survival rate increased from 54.9 to 81.3 %. The implantation rate, clinical pregnancy rate per embryo transfer, and per cycle were 28.2, 45.2, and 43.7 %, respectively, using the old formulations of cryosolutions. With the new solutions, the results reached 33.7, 54.1, and 54.1 %, respectively. All differences in results were statistically significant. The number of cancelled embryo transfers due to no survived embryos was 18 with the old solutions and 0 using the new solutions. CONCLUSION: With the new composition of solutions for slow freezing and thawing of embryos, significantly improved results were obtained. Additionally, the number of cancelled embryo transfers was reduced.

Influence of cleavage-stage embryo quality on the in-vitro fertilization outcome after single embryo transfer in fresh cycles.

OBJECTIVE: Embryo quality is crucial for determining the outcome of embryo implantation. This study aimed to assess the impact of embryo quality on the outcome of in vitro fertilization/single-embryo transfer (IVF-SET). MATERIALS AND METHODS: This retrospective study included 2531 fresh IVF-SET cycles, including 277 poor-quality and 2254 top-quality embryos. The clinical pregnancy rate, miscarriage rate, live birth, implantation rate, pregnancy outcome and complication were analyzed and compared. Risk factors associated with miscarriage rate and pregnancy complication were identified using logistics regression analysis. RESULTS: Top-quality embryos resulted in higher clinical pregnancy rate (30.5% vs. 12.6%, P < 0.001) and live birth rate (23.9% vs. 9.7%, P < 0.001) compared with poor-quality embryos. Logistics regression analysis revealed that embryo quality was not correlated with miscarriage rate (95% CI 0.33-1.89) and pregnancy complications (95% CI 0.12-7.84). Maternal age and body mass index was a risk factor for miscarriage rate (95% CI 1.05-1.22) and pregnancy complication (95% CI 1.01-1.29), respectively. CONCLUSION: Clinical miscarriage rate and pregnancy complication were embryo quality independent. Maternal age was the risk factor for miscarriage rate. Embryo quality did not affect miscarriage once a clinical pregnancy is achieved.