Luteal support is the administration of medication, generally progesterone, progestins or GnRH agonists, to increase the success rate of implantation and early embryogenesis, thereby complementing and/or supporting the function of the corpus luteum.
The live birth rate is significantly higher with progesterone for luteal support in IVF cycles with or without intracytoplasmic sperm injection (ICSI). Co-treatment with GnRH agonists further improves outcomes, by a live birth rate RD of +16% (95% confidence interval +10 to +22%). Luteal support with human chorionic gonadotropin (hCG) alone or as a supplement to progesterone has been associated with a higher risk of ovarian hyperstimulation syndrome (OHSS) and should therefore be avoided.
Formulations of progesterone or progestin 
The main formulations of progesterone or progestins for luteal support are:
- Formulations for intramuscular administrations
- Vaginal tablets or other inserts for intravaginal administration, such as endometrin
While daily intramuscular injections of progesterone-in-oil (PIO) have been the standard route of administration, PIO injections are not FDA-approved for use in pregnancy. A Cochrane review in 2011 found no evidence favoring a specific route of administration, dosage or duration of progesterone for luteal support.
- Van Der Linden, M.; Buckingham, K.; Farquhar, C.; Kremer, J. A. M.; Metwally, M. (2012). "Luteal phase support in assisted reproduction cycles". Human Reproduction Update 18 (5): 473. doi:10.1093/humupd/dms017.
- Kyrou, D.; Kolibianakis, E. M.; Fatemi, H. M.; Tarlatzi, T. B.; Devroey, P.; Tarlatzis, B. C. (2011). "Increased live birth rates with GnRH agonist addition for luteal support in ICSI/IVF cycles: A systematic review and meta-analysis". Human Reproduction Update 17 (6): 734–740. doi:10.1093/humupd/dmr029. PMID 21733980.
- Loose, Davis S.; Stancel, George M. (2006). "Estrogens and Progestins". In Brunton, Laurence L.; Lazo, John S.; Parker, Keith L. (eds.). Goodman & Gilman's The Pharmacological Basis of Therapeutics (11th ed.). New York: McGraw-Hill. pp. 1541–71. ISBN 0-07-142280-3.