Chapter 28 - Luteal phase support

Abstract

The luteal phase is one of the most important events necessary for the establishment of a successful pregnancy. The endometrium is a dynamic tissue, and the window of implantation is known to be present between days 19 and 24 of a spontaneous cycle. Luteal phase defects have been extensively studied over the years, most often in assisted reproduction cycles (ART) where controlled ovarian stimulation requires the use of gonadotropin-releasing hormone analogs, as well as an ovulation trigger to achieve timed final oocyte maturation. Altogether, these treatments suppress pituitary secretion of luteinizing hormone, required for the formation and early activity of the corpus luteum. Higher pregnancy rates have been shown in ART cycles in patients who receive progesterone compared with patients who do not, but there is no clear consensus on which formulation to use or route of administration, time of initiation, and duration of treatment once pregnancy is achieved in different types of cycles (fresh and frozen). Fresh and frozen-thawed cycles are completely different in hormonal dynamics and luteal phase.