B.D. Barnett

A controlled randomized trial evaluating the effect of lowered incubator oxygen tension on live births in a predominantly blastocyst transfer program

BACKGROUND The potentially damaging effect of free O(2) radicals to cultured embryos may be reduced by adding scavengers to the culture media or by reducing the incubator O(2) levels. However, lowering the O(2) in the culture environment can be expensive, troublesome and may not be justifiable. The objective of this study was to evaluate the effect of lowered incubator O(2) tension on live birth rates in a predominately Day 5 embryo transfer program. METHODS Two hundred and thirty first-cycle women undergoing routine IVF or ICSI with ejaculated sperm were randomized in a prospective clinical trial and stratified for patient age and physician. Embryos of patients were randomly assigned for culture in either a 21% O(2) (atmospheric) or 5% O(2) (reduced) environment. Clinical endpoints monitored were rates of implantation, clinical pregnancy, live birth and blastocyst cryopreservation. RESULTS Embryos cultured in a 5% O(2) environment consistently resulted in higher rates of live birth implantation (106/247, 42.9% versus 82/267, 30.7%; difference of 12.2% with 95% confidence interval (CI) of 3.9-20.3, P = 0.005) and live births (66/115, 57.4% versus 49/115, 42.6%; difference of 14.8% with 95% CI of 1.9-27.0, P = 0.043) when compared with rates among women whose embryos were cultured in an atmospheric O(2) environment. CONCLUSIONS The overall increase in live births demonstrated by this study indicates that the effort and expense to culture embryos in a low-O(2) environment is justified. The study was registered at clinicaltrials.gov. NCT00708487.

A randomized controlled study of human serum albumin and serum substitute supplement as protein supplements for IVF culture and the effect on live birth rates

BACKGROUND It has been speculated that the addition of proteins more complex than human serum albumin (HSA) to culture media may improve IVF outcomes. Whether the expense, labor and risk of adding additional human-derived protein to IVF media are warranted is a question unanswered. METHODS In a randomized controlled trial with couples undergoing routine IVF or ICSI, 528 patients were assigned to one of two treatment groups. Embryos were cultured in either media supplemented with HSA as a solitary protein supplement or in media supplemented with HSA+serum substitute supplement (SSS) from the 2PN stage until the time of embryo transfer. Clinical end-points monitored included implantation (total 1151 embryos) and live birth rates (total 528 patients). RESULTS The transfer of embryos cultured in HSA+SSS resulted in higher embryo implantation (289/571, 50.6% versus 254/580, 43.8%; difference 6.8% with 95% CI 1.0-12.7, P = 0.042) and live birth rates (167/266, 62.8% versus 142/262, 54.2%; difference 8.6% with 95% CI 0.1-17.3, P = 0.043) when compared with those of women whose embryos were cultured with HSA as the sole protein supplement. CONCLUSIONS SSS added to commercial HSA-supplemented embryo culture media resulted in an overall increase in implantation and live birth rates. It remains uncertain whether the use of human-derived blood products in culture media and the requirement for ultra-rigorous quality control measures make these findings applicable to the average IVF laboratory. Protein enrichment of media may significantly improve the blastocyst implantation rate, creating opportunities to transfer single blastocysts without compromising the live birth rate. The study was registered at clinicaltrials.gov. NCT00708383.