Examining the temperature of embryo culture in in vitro fertilization A randomized controlled trial comparing traditional core temperature 37°C to a more physiologic cooler temperature 36°C

Prior data suggested that tubal temperatures are lower than the IVF culture temperature of 37C. Paired comparison of human embryo culture at 36C and 37C reveals better outcomes at 37C.

Like Comment


Kathleen Hong, M.D., Hokyung Lee, M.S., Eric J. Forman, M.D., Kathleen M. Upham, B.S., Richard T. Scott, Jr., M.D., H.C.L.D.

Volume 102, Issue 3, Pages 767-773



To determine whether culture at a more physiologically cooler temperature, as suggested by limited human and animal data, would improve blastulation and pregnancy rates in human clinical IVF.


Paired randomized controlled trial.




Infertile couples (n = 52) with a female partner less than 42 years old with eight or more mature oocytes retrieved.


Mature oocytes obtained from a single cohort of oocytes were randomly divided into two groups; one was cultured at 37°C and the other at 36°C from the time of ICSI to the time of embryo transfer or vitrification. Paired embryo transfers were accomplished by transferring one euploid embryo from each group. DNA fingerprinting was used as needed to determine the outcome for each embryo.

Main Outcome Measure(s):

Rate of development of expanded blastocysts suitable for transfer or vitrification (primary outcome), fertilization, aneuploidy, and sustained implantation.


A total of 805 mature oocytes were cultured; 399 at 36°C and 406 at 37°C. Paired analysis demonstrated a higher rate of usable blastocyst formation per zygote at 37°C (48.4%) vs. at 36°C (41.2%). Rates of fertilization, aneuploidy, and sustained implantation were equivalent.


IVF culture at 36°C does not improve clinically relevant parameters of embryo development or sustained implantation rates.

Clinical Trial Registration Number:


Read the full text at: http://www.fertstert.org/article/S0015-0282(14)00542-1/fulltext

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.