Time-sensitive assessment of luteal phase progesterone after HCG ovulation triggering: another brick off the wall?

In recent years, there has been growing interest in understanding the dynamics of progesterone levels during the luteal phase after HCG-triggered ovulation. Recent studies have provided data showing a deviation from the natural ovulatory cycle, with peak progesterone concentrations occurring earlier and declining steadily thereafter, demonstrating that a fall in progesterone concentration early in the luteal phase was associated with lower rates of ongoing pregnancy. These findings highlight the importance of changes in progesterone concentration, rather than absolute concentrations, in determining optimal endometrial conditions. The disadvantages of HCG triggering, including the lack of a natural FSH surge and asynchronization between embryo age and endometrium receptivity, can be addressed by using gonadotrophin-releasing hormone agonist (GnRHa) triggering. GnRHa triggering induces both LH and FSH surges, ensures appropriate progesterone concentrations and offers flexibility in manipulating the luteal phase. Transitioning to GnRHa triggering could improve infertility treatment.