Luteal phase support in assisted reproductive technology

The purpose of this review is to discuss luteal support in assisted reproduction and to provide an evidence-based overview of the current options available. The luteal phase has been found to be defective in virtually all of the stimulation protocols used for in-vitro fertilization. Common mechanisms such as supraphysiological levels of estradiol, decreased output of luteinizing hormone, inhibition of the corpus luteum and asynchronization of estradiol and progesterone may be involved in insufficient function of the corpus luteum in assisted reproductive technology. Gonadotropin releasing hormone agonist undoubtedly provides benefits in stimulated cycles, however it also has adverse effects, inhibition of the corpus luteum together with supraphysiological hormonal profiles finally leading to luteal phase defects. Luteal phase support with human chorionic gonadotropin or progesterone after assisted reproduction results in increased pregnancy rates. The role of luteal phase support in these cycles has also been recently elucidated. Use of human chorionic gonadotropin for luteal phase support is associated with a marked increase in the risk of ovarian hyperstimulation syndrome, therefore progesterone is the preferred choice. Data on the benefits of estrogen supplementation are conflicting. Among the routes of progesterone administration, reductions in pregnancy rates are noted on oral administration. In spite of a lack of statistical significance, the intramuscular route seems to be more beneficial than the vaginal route when considering rates of ongoing pregnancy and live birth. Further clarification is needed on the ideal dose, the optimal route and the duration of progesterone administration in assisted reproduction.