Does hyaluronan improve embryo implantation?

Purpose of review Taking into consideration the increasing interest on hyaluronan and its biological as well as physiological properties, this review will focus on the role of this molecule in human embryo implantation. Recent findings Several studies have been performed up to date in order to assess whether the addition of hyaluronan in the human embryo culture system can improve pregnancy and implantation rates, including one retrospective and six randomized controlled trials. On the one hand, four of those studies showed significant increase in clinical pregnancy and/or implantation rates after using embryo transfer medium containing high concentration of hyaluronan. On the other hand, three studies did not demonstrate any significant improvement in clinical pregnancy and implantation rates. However, regardless of statistical significance, almost all studies demonstrate higher pregnancy and implantation rates after using embryo transfer medium containing high concentration of hyaluronan. Summary Up to date, the results regarding the role of hyaluronan in human embryo implantation are still conflicting and, thus, further prospective randomized clinical trials are necessary to draw solid conclusions.