The good, the bad and the ugly of luteal phase stimulations

Abstract

Early follicular phase start of ovarian stimulation in Assisted Reproductive Technology (ART) is only required if a fresh embryo transfer is planned. A shift from fresh to frozen embryo transfers has characterized ART treatments recently and combined with the trend towards treatment individualization and simplification, facilitated random start stimulation. Luteal phase stimulations, commenced between ovulation and the next menses, have gained momentum and the good, the bad and the ugly sides become obvious with the increasing numbers performed as such.Unprotected intercourse during the follicular phase or around ovulation can result in an unknown and undetectable conception at the time of stimulation start. Aside from the theoretical implications for embryo development from exposure to stimulation medication, the embryo derived hCG may cause ovarian hyperstimulation syndrome.Stimulation duration and gonadotropin consumption appear to be longer and higher than in early follicular phase start, although the number of retrieved / mature oocytes is comparable or, in some instances, higher. On the other hand, elevated progesterone levels during the luteal phase may prevent premature ovulation and, in theory, might replace pituitary suppression using GnRH-antagonists or exogeneous progestins. Furthermore, the flexibility in stimulation timings will meet the needs of patients with time constraints.