Reproductive Outcome of IVF Treatment in Relation to the Early Luteal Phase Trajectory of Progesterone and Other Corpus Luteum Related Hormones

The early luteal phase after ovarian stimulation and final oocyte maturation using a bolus trigger of hCG is an area that has not received the same attention as regimes and protocols for ovarian stimulation during the follicular phase. The hCG trigger has been considered the golden standard since the beginning of the IVF era almost four decades ago. The hCG trigger serves two main functions: 1) it induces oocytes to advance meiosis to the metaphase of the second meiotic division ready for fertilization and further development, 2) secures stimulation of the corpora lutea to secrete progesterone (P4) during the early luteal phase due to its relatively long half-life. However, recent studies have suggested that each of these two functions may be optimized on their own and that better alternatives to the hCG trigger may be developed including a more physiological trigger for final maturation of follicles and individualized luteal phase support. However, only recently has the early luteal phase after IVF treatment using an hCG bolus trigger been described in studies involving more than just a few patients. These studies suggested that the unphysiological effects of the hCG trigger may be divided into three different categories: 1) The timing of the initiation of hCG and progesterone rise is much faster after an hCG trigger than in the natural menstrual cycle 2) the maximal concentrations of hCG and progesterone considerably exceed those naturally observed 3) The timing of the peak progesterone concentration following an hCG trigger is advanced several days compared to the natural cycle. How each of these effects influences pregnancy outcome in treatment cycles are currently unknown. Further, does characteristics shortly after administration of the hCG trigger for final oocyte maturation subsequently affect the reproductive outcome, and does this provide an opportunity for correcting or improving the luteal phase support given, with the improvement of clinical pregnancy rate as a result is also unknown. The aim of this study is to evaluate the trajectories of four hormones important for corpora lutea function (i.e. P4, 17-OH-P4, hCG, and inhibin-A) during the early luteal phase in women undergoing IVF treatment with luteal phase support given in the form of exogenous P4 administration and evaluate whether clinical pregnancy rates are related to specific characteristics of the early luteal phase. By including the measurements of 17-OH-P4 and inhibin-A the study will obtain an evaluation of the function of corpora lutea itself independent of the P4 administration provided.