Steroid hormones hold a major role in female fertility and their proper
utilisation and monitoring in modern assisted reproduction protocols is
important. Oocyte maturation and endometrial receptivity are the two
major factors that appear to be related to a successful outcome in
Assisted Reproductive Technology (ART). Many reports suggest that oocyte
immaturity accounts for a considerable loss of efficiency in ART, mainly
due to the poor quality of the obtained embryos and their inability to
develop normally. Oestrogen appears to exert its effects on the
cytoplasmic maturation of the oocyte, while progesterone has been shown
to accelerate meiotic resumption. Moreover, ovarian stimulation appears
to affect the normal luteal function and shifts in the window of
implantation as a response to hormonal supplementation have also been
observed. The ethical limitations in conducting in vivo studies of human
implantation, have led to an indirect hormonal- and morphologic-oriented
assessment of endometrial receptivity. The two main protocols of luteal
support involve either progesterone supplementation or hCG
administration, whereas the combined supplementation with oestradiol
remains controversial. This brief review aims to summarize the current
knowledge on steroidal actions during the above processes and to address
their potential use in the improvement of current ART protocols. (C)
2008 Elsevier Ltd. All rights reserved
