The present invention relates generally to the fields of reproductive medicine. More specifically, the present invention relates to a novel human embryo co-culture system to improve human embryo growth in vitro and, consequently, increase pregnancy rates in infertile women undergoing in vitro fertilization (IVF) treatment. More particularly, the present invention relates to a method of growing an embryo to a blastocyst stage of development comprising the step of coculturing said embryo in the presence of a population of cumulus cells.