The present invention relates to a novel melatonin based formulation particularly a topical liquid composition of melatonin (or analog thereof) suitable for use in intrauterine washing performed during medically assisted reproduction (e.g. in vitro fertilisation IVF). Melatonin is notoriously unstable especially in solution. The compositions of the invention exhibit high stability which allows them to be kept for prolonged periods before their eventual use in the inhibition or prevention of embryonic implantation failure.
