The document discusses luteal phase support (LPS) in assisted reproductive technology (ART) cycles. It notes that abnormal luteal function can occur after controlled ovarian stimulation, necessitating LPS. It reviews various LPS options including human chorionic gonadotropin and progesterone administered via different routes. Vaginal progesterone is found to effectively increase endometrial levels while intramuscular progesterone yields the highest serum levels. The document concludes that LPS is necessary to optimize ART outcomes and that intramuscular or vaginal progesterone are equally effective options.