Comparing 36.5°C with 37°C for human embryo culture: a prospective randomized controlled trial

Area of Science:

• Reproductive biology
• In vitro fertilization (IVF)
• Embryology

Background:

• Optimizing in vitro culture conditions is crucial for successful IVF outcomes.
• Human embryo development is sensitive to environmental factors, including temperature.

Purpose of the Study:

• To compare the efficacy of two incubation temperatures (36.5°C vs. 37°C) on human embryo development in vitro.
• To assess the impact of culture temperature on key IVF metrics such as fertilization, embryo quality, and blastocyst formation.

Main Methods:

• Prospective, double-blind, randomized controlled trial involving 412 women undergoing IVF.
• Oocytes and embryos were cultured at either 36.5°C (intervention) or 37°C (control).
• Evaluated parameters included cleavage rates, fertilization rates, embryo quality, and blastocyst development.

Main Results:

• Culture at 36.5°C showed a higher cleavage rate but lower fertilization rates.
• Fewer high-quality embryos on day 3 and reduced blastocyst formation rates were observed at 36.5°C.
• Significantly fewer high-quality and cryopreserved blastocysts were obtained when culturing at 36.5°C compared to 37°C.

Conclusions:

• While 36.5°C enhanced cleavage rates, 37°C proved superior for overall human embryo development in vitro.
• The study recommends continuing the use of 37°C for human embryo culture due to better outcomes in embryo quality and blastocyst development.
• Further research is needed to determine optimal temperatures for specific stages of in vitro embryo development.